Animals That Start with X: Rare and Remarkable Species

The animal kingdom contains very few species with common names beginning with the letter X. This article examines the best documented examples, including the X-ray tetra, the Xenopus frog genus, and several lesser known species such as Xerus ground squirrels and Xiphias swordfish. The scarcity of X named animals reflects the historical origins of common names in English, Latin, and Greek instead of any biological rarity. For students, researchers, and life science professionals, understanding these species provides insight into taxonomy, evolutionary adaptation, and biomedical research applications.

Why So Few Animals Start with X

The letter X appears infrequently at the beginning of English words. Most animal common names derive from Latin, Greek, or local languages, and few of those languages use X as an initial letter. The International Code of Zoological Nomenclature requires scientific names to follow Latin grammar, which further limits X initial names. When X does appear, it typically comes from Greek roots where the letter xi or chi was transliterated.

The practical consequence is that a complete list of animals starting with X remains short. The most recognized examples include the X-ray tetra, Xenopus frogs, Xerus squirrels, Xiphias swordfish, and Xantus hummingbird. Several additional species carry X names in specific regions or scientific contexts. Researchers searching for X named animals should also consider that some species have multiple common names, and one name may begin with X while another does not.

At a Glance: Notable Animals That Start with X

The X-ray Tetra: A Transparent Aquarium Species

The X-ray tetra, scientifically named Pristella maxillaris, earns its common name from its translucent body. The swim bladder and vertebral column remain visible through the skin and muscle tissue. This transparency gives the fish its X-ray appearance and makes it one of the most recognizable aquarium species with an X name.

Natural Habitat and Behavior

X-ray tetras inhabit slow moving rivers and streams in South America, particularly in Brazil, Venezuela, and Guyana. They prefer soft, slightly acidic water with dense vegetation. In the wild, they form schools and feed on small invertebrates, insect larvae, and plant matter. Their small size, reaching approximately 5 centimeters in length, makes them suitable for community aquariums.

Aquarium Management Considerations

For aquaculture and aquarium professionals, X-ray tetras require stable water conditions. The recommended temperature range falls between 24 and 28 degrees Celsius. Water pH should remain between 6.0 and 7.5. These fish tolerate a range of water hardness but perform best in soft to moderately hard water. Regular water changes and filtration maintain water quality and reduce stress.

Breeding X-ray tetras in captivity requires attention to water conditions and nutrition. Condition breeding pairs with live or frozen foods such as brine shrimp and bloodworms. Provide fine leaved plants or spawning mops for egg deposition. Remove adult fish after spawning because they may consume eggs. Fry hatch within 24 to 36 hours and require infusoria or commercially prepared fry food for the first days.

Common Failure Patterns in X-ray Tetra Maintenance

Aquarium keepers most often lose X-ray tetras to poor water quality and sudden temperature changes. Overcrowding causes stress and increases disease susceptibility. Introducing new fish without quarantine can spread parasites and bacterial infections. Professional escalation criteria include persistent fin clamping, rapid gill movement, or unexplained mortality. In these cases, consult an aquatic veterinarian or experienced fish health specialist.

Xenopus Frogs: The Biomedical Research Standard

The Xenopus genus contains entirely aquatic frogs native to sub-Saharan Africa. Two species dominate research and laboratory use: Xenopus laevis and Xenopus tropicalis. The complete genomes of both species have been sequenced, annotated, and made publicly available [17]. These frogs serve as model organisms across developmental biology, genetics, and biomedical research.

Xenopus laevis: The Allotetraploid Model

Xenopus laevis, commonly called the African clawed frog, has a remarkable genomic history. Researchers sequenced the X. laevis genome and compared it to the related diploid X. tropicalis genome. The analysis characterized the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes marked by distinct families of fossil transposable elements [22].

Based on the activity of these elements and the age of hundreds of unitary pseudogenes, researchers estimate that the two diploid progenitor species diverged around 34 million years ago and combined to form an allotetraploid around 17 to 18 million years ago [22]. More than 56 percent of all genes were retained in two homoeologous copies. Protein function, gene expression, and the amount of conserved flanking sequence all correlate with retention rates [22].

The subgenomes have evolved asymmetrically. One chromosome set more often preserves the ancestral state, while the other experiences more gene loss, deletion, rearrangement, and reduced gene expression [22]. This asymmetric evolution makes X. laevis a valuable system for studying genome evolution and gene regulation.

Xenopus tropicalis: The Diploid Counterpart

Xenopus tropicalis lives in hot, equatorial regions of Africa, whereas X. laevis resides in the cooler climates of southern Africa [17]. The two species inhabit markedly different environments, and their proteins reflect these differences. Research on endonuclease G proteins in the Xenopus genus found that EndoG proteins from the psychrophilic X. laevis exhibit increased contents of charged and polar residues, elevated isoelectric points, higher intramolecular interaction energies, B factors, molecular void volumes, and solvent accessibilities [17].

In contrast, EndoG proteins from the thermophilic X. tropicalis show decreased contents of nonpolar and aromatic amino acids, lower hydrophobicity, buried surface area, and molecular packing density [17]. These observed differences strongly suggest that temperature plays a dominant role in EndoG diversification [17]. Evaluation of intramolecular interaction energies appears to be a particularly sensitive and discriminative framework for assessing protein divergence at the structural level [17].

Xenopus in Developmental Biology Research

The spinal circuit controlling swimming locomotion in hatchling Xenopus frog tadpoles was one of the first vertebrate central pattern generators investigated in detail. Research over four decades has led to a detailed understanding of the motor and interneurons that comprise the central pattern generator, their electrical properties, and synaptic connectivity [18].

The swimming system includes initiation and termination by specific sensory pathways and switching of motor programs from swimming to struggling. Intrinsic mechanisms confer short term motor memory via dynamic sodium pumps [18]. After hatching, there is an initial and rapid development of the swimming output in the prelude to continuous free swimming and metamorphosis that relies partly on the incorporation of modulatory systems that descend from the brainstem, including aminergic and nitrergic influences [18].

Xenopus fraseri: Resolving a Taxonomic Enigma

The taxonomic status of Xenopus fraseri, Fraser's clawed frog, remained uncertain for more than 150 years. Modern researchers used high resolution techniques to examine morphological variation and generated complete mitochondrial genome sequences from all Xenopus species, including type specimens over 150 years old [23].

The results demonstrated that X. fraseri is distinct from other species, firmly placed this species within a phylogenetic context, and identified its minimal geographic distribution in northern Ghana and northern Cameroon [23]. Xenopus fraseri was formerly thought to be a rainforest endemic placed alongside species in the amieti species group. In fact, this species occurs in arid habitat on the borderlands of the Sahel and is the smallest member of the muelleri species group [23].

The taxonomic enigma of Fraser's frog was a combined consequence of sparse collection records, interspecies conservation and intraspecific polymorphism in external anatomy, and type specimens with unusual morphology [23].

Laboratory Management of Xenopus Colonies

Institutions maintaining Xenopus colonies follow established husbandry protocols. Water quality parameters include temperature, pH, conductivity, and ammonia levels. Adult X. laevis require larger tanks than X. tropicalis due to size differences. Filtration systems must handle high bioload from aquatic frogs.

Breeding programs use hormone stimulation to induce ovulation and spermiation. Eggs are collected and raised in shallow water with appropriate temperature control. Tadpoles require specific feeding regimens and water conditions. Metamorphosis occurs over several weeks, and juvenile frogs need gradual transition to adult care protocols.

Professional escalation criteria for Xenopus colonies include unexplained mortality, skin lesions, weight loss, or behavioral changes. Consult a laboratory animal veterinarian when these signs appear. Record keeping should document water quality parameters, feeding rates, breeding success, and health observations.

Xerus Ground Squirrels: African Rodents

The genus Xerus contains several species of ground squirrels native to Africa. These rodents live in arid and semiarid regions, where they dig extensive burrow systems. Their common name starts with X, making them one of the few mammal genera with this distinction.

Species Diversity and Distribution

The genus Xerus includes species such as the unstriped ground squirrel, the striped ground squirrel, and the Cape ground squirrel. Each species occupies distinct geographic ranges across eastern, southern, and western Africa. They prefer open habitats including savannas, grasslands, and scrublands.

Behavioral Ecology

Xerus squirrels are diurnal and social. They live in colonies with complex social structures. Their burrow systems provide protection from predators and temperature extremes. Diet consists primarily of seeds, nuts, roots, and insects. They forage during daylight hours and retreat to burrows at night.

Conservation and Management

Most Xerus species maintain stable populations. Habitat loss and fragmentation pose localized threats. In agricultural areas, farmers may view ground squirrels as pests due to crop consumption. Management strategies include habitat preservation and nonlethal deterrents where conflicts arise.

Xiphias gladius: The Swordfish

Xiphias gladius, the swordfish, represents one of the most commercially important fish species with an X name. The genus name Xiphias derives from the Greek word for sword, referring to the elongated bill that characterizes this species.

Biology and Distribution

Swordfish inhabit tropical and temperate oceans worldwide. They are highly migratory and undertake extensive movements across ocean basins. Adults can reach lengths exceeding 4 meters and weights over 500 kilograms. Their distinctive bill is used to slash and stun prey, which includes fish and squid.

Fisheries and Management

Commercial swordfish fisheries operate in the Atlantic, Pacific, and Indian Oceans. Management measures include catch limits, minimum size requirements, and gear restrictions. Longline fisheries target swordfish, and bycatch mitigation measures aim to reduce interactions with sea turtles, seabirds, and marine mammals.

Research Applications

Swordfish research contributes to understanding migratory patterns, population structure, and stock assessment. Genetic studies inform management decisions. Temperature and depth data from tagged fish reveal habitat preferences and feeding behavior.

Xantus Hummingbird: A Regional Endemic

The Xantus hummingbird, Basilinna xantusii, is named after John Xantus, a Hungarian zoologist. This species is endemic to the Baja California Peninsula in Mexico. Its restricted range makes it a subject of biogeographic interest.

Habitat and Ecology

Xantus hummingbirds inhabit scrublands, woodlands, and gardens across Baja California. They feed on nectar from a variety of flowering plants and supplement their diet with small insects. Their breeding season coincides with peak flower availability.

Conservation Status

The species maintains a stable population within its limited range. Habitat protection and awareness of its endemic status support conservation efforts. Birdwatchers and researchers visiting Baja California may encounter this species in suitable habitat.

Other Species with X Names

Several additional species carry X names in scientific or regional contexts. The Xerus genus provides the clearest example of a mammal genus with an X initial. The Xylocopa genus contains carpenter bees, though the common name typically uses carpenter bee instead of Xylocopa. Xestia moths represent a diverse genus within the Noctuidae family.

Xylocopa Carpenter Bees

Xylocopa species are large, robust bees that nest in wood. They are important pollinators for many plant species. Their common name derives from their nesting behavior instead of their scientific name. Farmers and gardeners may encounter these bees in dead wood, fence posts, and structural timber.

Xestia Moths

The Xestia genus includes numerous moth species distributed across temperate regions. They are typically nocturnal and attracted to lights. Some species are agricultural pests, while others serve as prey for birds and bats.

The Role of X in Scientific Nomenclature

The letter X appears in scientific names for various reasons. Some names derive from Greek roots where X represents the letter chi. Others use X to describe physical characteristics, such as the Xiphias swordfish. Taxonomic revisions occasionally create new X names when species are reclassified.

X Chromosome Research Connections

The X chromosome has significant biological importance beyond animal naming. X chromosome inactivation, discovered by Mary Lyon in 1961, results in random silencing of one X chromosome in female mammals [5]. Lyon predicted many features of X inactivation, including the existence of an X inactivation center, the role of L1 elements in spreading of silencing, and the existence of genes that escape X inactivation [5].

In female somatic cells of mammalian species, one X chromosome is inactivated to ensure dosage equality of X encoded genes between females and males during development and adulthood [8]. X chromosome inactivation involves various epigenetic mechanisms, including RNA mediated gene silencing in cis, DNA methylation, and changes in chromatin modifications and composition [8].

The XCI process starts with counting of the number of X chromosomes present in a nucleus, and initiation of XCI follows if this number exceeds one per diploid genome [8]. X encoded RNF12 has been identified as a dose dependent activator of XCI. Other factors, including the pluripotency factors OCT4, SOX2, and Nanog, have been implicated to play a role in suppression of initiation of XCI [8].

Fragile X Related Conditions

The fragile X syndrome, fragile X tremor ataxia syndrome, and premature ovarian insufficiency are conditions related to the X chromosome folate sensitive fragile site FRAXA [10]. These conditions are considered a family of disorders under the general designation of FRAXopathies [10]. Understanding the pathogenic mechanisms that lead to distinct phenotypes, starting from related mutations, is generating promising therapeutic approaches [10].

X Ray Technology in Animal Research

The letter X also connects to X ray technology used in veterinary and research settings. X ray based techniques provide noninvasive imaging of animal tissues and support diagnostic and research applications.

Bioimaging Metallomics

Bioimaging in metallomics involves metal and metalloid distribution in animal tissues. Techniques include laser ablation inductively coupled plasma mass spectrometry, secondary ion mass spectrometry, synchrotron based X ray fluorescence, and electron microscopy including transmission electron microscopy, scanning electron microscopy, and energy dispersive X ray spectroscopy [6].

These techniques provide qualitative and quantitative imaging of elements in cells and animal tissues, including the brain, liver, hair, eye, teeth, and bone [6]. Sample preparation for bioimaging is briefly discussed in the literature, and the usefulness of element bioimaging is demonstrated across multiple tissue types [6].

X Ray Crystallography in Structural Biology

X ray crystallographic data have been obtained for several fragments of the vimentin dimer, an intermediate filament protein [9]. Intermediate filaments, together with microtubules and actin microfilaments, constitute the integrated, dynamic filament network present in the cytoplasm of metazoan cells [9]. This network is critically involved in division, motility, and other cellular processes [9].

The elementary building block of intermediate filaments is a highly elongated, rod like dimer based on an alpha helical coiled coil structure [9]. Assembly of cytoplasmic intermediate filament proteins begins with a lateral association of dimers into tetramers and gradually into unit length filaments. Subsequently, unit length filaments start to anneal longitudinally, ultimately yielding mature intermediate filaments after a compaction step [9].

X Ray Tube Control in Imaging Systems

Control schemes for quickly starting X ray tubes have been developed for imaging applications [24]. These technical developments support efficient operation of X ray equipment used in veterinary and research settings. The IEEE Transactions on Industry Applications published research on this topic in 2011 [24].

Practical Assessment Steps for Species Identification

When verifying whether an animal name starts with X, follow a systematic approach. First, confirm the common name in standard references. Second, check the scientific name for X initial. Third, verify the geographic range and habitat. Fourth, consult taxonomic databases for current classification.

Step 1: Confirm Common Name

Standard field guides and taxonomic databases provide authoritative common names. Regional variations exist, so confirm the name used in your context. For example, the X ray tetra is also called the goldfinch tetra in some references.

Step 2: Verify Scientific Name

Scientific names follow standardized nomenclature. The Integrated Taxonomic Information System and similar databases provide current classifications. Verify both genus and species names.

Step 3: Check Geographic Range

Distribution data confirm whether a species occurs in your region. Range maps and occurrence records support identification. For rare or endemic species, geographic context is essential.

Step 4: Consult Taxonomic Databases

Online databases provide updated classifications and synonymy. Taxonomic revisions can change names, so current sources are essential. Cross reference multiple databases to confirm accuracy.

Records and Measurements for Research Documentation

Researchers documenting X named animals should maintain standardized records. Include species identification, date, location, habitat description, and observer information. Photographs and specimen collections support verification. Genetic samples, when collected, require proper permits and storage protocols.

Field Observation Records

Field observations should note behavior, group size, and environmental conditions. For aquatic species, record water temperature, pH, and clarity. For terrestrial species, note vegetation type and weather conditions. Standardized forms improve data comparability across observers.

Laboratory Records

Laboratory studies require detailed records of experimental conditions, sample handling, and analytical methods. For Xenopus research, document water quality parameters, feeding schedules, and breeding outcomes. For genetic studies, record sample origins and storage conditions.

Data Management

Digital databases facilitate data sharing and analysis. Use standardized formats and metadata descriptions. Backup systems protect data integrity. Ethical considerations include proper permits for specimen collection and compliance with institutional animal care requirements.

Common Failure Patterns in Species Documentation

Misidentification represents the most common failure in documenting X named animals. Similar looking species may be confused, especially when common names vary regionally. Taxonomic revisions can change names, making older records outdated.

Misidentification Risks

The X ray tetra may be confused with other small characins. Xenopus species require genetic or detailed morphological analysis for reliable identification. Xerus species overlap in some regions, requiring careful observation of diagnostic features.

Record Keeping Failures

Incomplete records reduce the value of observations. Missing dates, locations, or habitat descriptions limit data utility. Poorly preserved specimens degrade over time. Inadequate permits create legal and ethical problems.

Data Interpretation Errors

Overinterpreting limited observations leads to incorrect conclusions. Small sample sizes may not represent population characteristics. Confirmation bias affects interpretation when researchers expect particular outcomes.

Limitations of X Named Animal Lists

Any list of animals starting with X has inherent limitations. Common names vary by language and region. Scientific names change with taxonomic revisions. New species are described regularly, and some may receive X names.

Language and Regional Variation

English common names differ from names in other languages. A species with an X name in English may have a different name elsewhere. Regional dialects within English also vary. Researchers should specify which naming convention they use.

Taxonomic Instability

Ongoing taxonomic research revises classifications. Species may be split, merged, or moved between genera. Names change accordingly. The Uropsilus shrew moles exemplify this challenge, with integrative taxonomic revision combining genomic, morphological, and geographic evidence to reassess species boundaries [13].

Incomplete Knowledge

Many species remain undescribed. Remote habitats harbor undocumented diversity. Genetic analysis reveals cryptic species that look identical but are reproductively isolated. The known list of X named animals will likely change as knowledge advances.

Welfare and Safety Context

Working with X named animals requires attention to welfare and safety. Aquatic species need appropriate water quality. Laboratory animals require veterinary oversight. Wild species demand respect for their natural behavior and habitat.

Aquatic Species Welfare

X ray tetras and Xenopus frogs require specific water conditions. Ammonia and nitrite levels must remain low. Temperature stability prevents stress. Appropriate tank size reduces crowding effects. Regular health monitoring detects problems early.

Laboratory Animal Welfare

Xenopus colonies fall under institutional animal care regulations. Veterinary oversight ensures proper housing, feeding, and health care. Procedures require approval through institutional animal care and use committees. Pain and distress must be minimized.

Wild Species Safety

Observing wild X named animals requires maintaining safe distances. Do not approach nesting sites or burrows. Avoid disturbing natural behaviors. Follow local regulations for wildlife observation and photography.

Professional Escalation Criteria

Recognize when to consult specialists. For aquarium fish health problems, contact an aquatic veterinarian. For laboratory animal issues, consult the attending veterinarian. For wild species concerns, contact wildlife authorities.

Aquatic Health Concerns

Escalate when fish show persistent signs of disease, unexplained mortality occurs, or water quality parameters remain abnormal despite corrective actions. Document observations and treatments before consultation.

Laboratory Concerns

Escalate when Xenopus colonies experience unexpected deaths, breeding failure, or behavioral changes. Provide complete records to veterinary staff. Follow institutional protocols for reporting animal welfare concerns.

Wildlife Concerns

Escalate when wild populations show signs of disease, habitat destruction threatens known sites, or illegal collection is suspected. Contact appropriate authorities with location data and observations.

Frequently Asked Questions

What is the most well known animal that starts with X?

The X ray tetra is the most recognized aquarium species with an X name. Its transparent body reveals the spine and swim bladder, giving it the X ray appearance. The Xenopus frog genus is the most significant X named animal in biomedical research due to its use as a model organism.

Are there any mammals that start with X?

The Xerus genus of African ground squirrels is the primary mammal genus with an X name. Several species exist across Africa, including the Cape ground squirrel and the unstriped ground squirrel. These rodents live in arid and semiarid habitats and dig extensive burrow systems.

Why are there so few animals that start with X?

The scarcity reflects linguistic patterns instead of biological rarity. Few English words begin with X, and most animal common names derive from languages that rarely use X as an initial letter. Scientific names follow Latin grammar, which also limits X initial names.

What is the difference between Xenopus laevis and Xenopus tropicalis?

Xenopus laevis is an allotetraploid species with two homoeologous subgenomes, while Xenopus tropicalis is diploid. X. laevis is larger and lives in cooler southern African climates. X. tropicalis is smaller, lives in hot equatorial regions, and has a simpler genome that facilitates genetic studies.

Is the X ray tetra suitable for home aquariums?

Yes, X ray tetras are suitable for community aquariums. They reach about 5 centimeters in length and prefer soft, slightly acidic water. Stable water temperature between 24 and 28 degrees Celsius and regular water changes support their health. They school with conspecifics and do best in groups.

What is the X chromosome inactivation process?

X chromosome inactivation results in random silencing of one X chromosome in female mammals to ensure dosage equality of X encoded genes between females and males [5]. The process involves counting X chromosomes, initiation of inactivation, and spreading of silencing across the chromosome [8].

Are there any birds that start with X?

The Xantus hummingbird, Basilinna xantusii, is a bird species with an X name. It is endemic to the Baja California Peninsula in Mexico. The species maintains a stable population within its limited range and inhabits scrublands, woodlands, and gardens.

How do researchers identify Xenopus species?

Researchers use genetic analysis and morphological examination to identify Xenopus species. Complete mitochondrial genome sequences support phylogenetic placement [23]. High resolution morphological techniques reveal diagnostic features. For some species, type specimens over 150 years old have been analyzed successfully [23].

Related Articles

• Animal Biology
• Animal Research
• Biology Facts
• Biotech X Ray
• x ray tech programs

References and Further Reading

• NCBI Literature Resources. National Center for Biotechnology Information.
• PubMed. National Library of Medicine.
• Ganciclovir.. Profiles of drug substances, excipients, and related methodology, 2018.
• Canine noninflammatory alopecia: An approach to its classification and a diagnostic aid.. Veterinary pathology, 2023.
• X-chromosome inactivation and escape.. Journal of genetics, 2015.
• Bioimaging Metallomics.. Advances in experimental medicine and biology, 2018.
• Melatonin: comprehensive profile.. Profiles of drug substances, excipients, and related methodology, 2013.
• X-changing information on X inactivation.. Experimental cell research, 2010.
• Molecular architecture of intermediate filaments.. BioEssays : news and reviews in molecular, cellular and developmental biology, 2003.
• The FRAXopathies: definition, overview, and update.. American journal of medical genetics. Part A, 2011.
• Cross-Species Transmission and Recombination Between Feline and Canine Coronaviruses in Jiangsu-Zhejiang Region in 2025.. 2026.
• Cross-species comparative transcriptomic analysis of spermatozoa reveals species-specific regulatory networks linked to fertilization-associated genes in cattle, sheep and goats.. 2026.
• Integrative taxonomic revision of Uropsilus (Uropsilinae, Talpidae) combining genomic, morphological and geographic evidence.. 2026.
• Two new species of Myxodavisia (Myxosporea: Sinuolineidae) from the gallbladder of two marine fishes from the South China Sea.. 2026.
• A universal 6iL/E4 culture system for deriving and maintaining embryonic stem cells across mammalian species.. 2026.
• Description of a New Species of Caliscelidae from the High Altitude Region of Xizang Based on Morphological and Molecular Evidence &lt,sup&gt,†&lt,/sup&gt,.. 2026.
• Thermoadaptation of EndoG proteins in the Xenopus frog genus. bioRxiv, 2026.
• Neural control of swimming in hatchling Xenopus frog tadpoles. 2020.
• Heterogeneity of synonymous substitution rates in the Xenopus frog genome. PLoS ONE, 2020.
• Evolution of the MHC: antigenicity and unusual tissue distribution of Xenopus (frog) class II molecules.. Molecular Immunology, 1990.
• Inference of Genetic Network of Xenopus Frog Egg : Improved Genetic Algorithm. Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2006.
• Genome evolution in the allotetraploid frog Xenopus laevis. Nature, 2016.
• Xenopus fraseri: Mr. Fraser, where did your frog come from?. PLoS ONE, 2019.
• Control scheme for quickly starting X-ray tube. Ieej Transactions on Industry Applications, 2011.
• Mouse and large-animal toxicology studies of twelve antitumor agents: Relevance to starting dose for Phase I clinical trials. Cancer Chemotherapy and Pharmacology, 1979.
• Intracerebral delivery of Carboplatin in combination with either 6 MV Photons or monoenergetic synchrotron X-rays are equally efficacious for treatment of the F98 rat glioma. Journal of Experimental and Clinical Cancer Research, 2012.
• Stress-induced disturbances of the structure of periodont tissue in experiment on animals. Medical News of North Caucasus, 2018.

This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.