Universal Decimal Classification

  1. A cappella music. Unaccompanied vocal music. Rounds
  2. Abnormal psychology
  3. Above sea level. Surface relief. Above ground generally. Mountains
  4. Abstract art. Non-figurative art
  5. Accidents. Risks. Hazards. Accident prevention. Personal protection. Safety
  6. Accommodation desires and their fulfilment. Safeguarding accommodation
  7. Accountancy
  8. Accoutrements. Beltmaking. Leather equipment and analogous products
  9. Acoustic measurements
  10. Activity and organizing. Communication and control theory generally (cybernetics). 'Human engineering'
  11. Activity of international and intergovernmental organizations
  12. Acts of worship (by participants)
  13. Addresses. Lectures. Speeches
  14. Administrative and auxiliary services: personnel, organization
  15. Administrative departments of libraries
  16. Administrative law
  17. Administrative management. Secretariat
  18. Adults. Grown-ups
  19. Advanced architectures. Non-Von Neumann architectures
  20. Aerial sports
  21. Aerodynamics
  22. Aesthetics and film
  23. Aetiology. Science of the causes of disease
  24. Afghanistan. Islamic Republic of Afghanistan. Afganistan. Jomhūrī-ye Eslāmī-ye Afġānistān. Da Afġānistān Islāmī Jomhoriyat
  25. Africa
  26. African Continental Ancestry Group
  27. African islands of the Indian and South Atlantic oceans
  28. Afrikaans
  29. Afro-Asiatic (Hamito-Semitic) languages
  30. Afro-Asiatic, Nilo-Saharan, Congo-Kordofanian, Khoisan languages
  31. Afro-Asiatic, Nilo-Saharan, Congo-Kordofanian, Khoisan languages
  32. Agricultural hydraulics. Irrigation, drainage and reclamation engineering
  33. Agricultural machines, implements and equipment
  34. Agricultural operations
  35. Agriculture and related sciences and techniques. Forestry. Farming. Wildlife exploitation
  36. Agriculture in general
  37. Ainu
  38. Air and space transport engineering. Aeronautics and aircraft. Rockets and missiles. Astronautics and spacecraft
  39. Air-force penal law
  40. Albania. Republic of Albania. Shqipëria. Republika e Shqipërisë
  41. Albanian
  42. Albanian language
  43. Albanian literature
  44. Algae. Phycology
  45. Algebra
  46. Algeria. People’s Democratic Republic of Algeria. Al Jaza'ir. Al Jumhuriyah al Jaza'iriyah ad Dimuqratiyah ash Sha'biyah
  47. Alimentation. Eating. Digestion. Nutrition
  48. All languages natural or artificial
  49. Almanacs. Calendars (of all types)
  50. Alphabetic writing systems
  51. Altaic languages
  52. Amateur handicrafts. Technical hobbies
  53. America, North and South. The Americas
  54. American indigenous languages
  55. American indigenous languages
  56. American Native Continental Ancestry Group
  57. Amphibia
  58. Anabaptists
  59. Analysis
  60. Analysis and synthesis of sounds
  61. Analysis by biological and biochemical reactions. Biological methods used for analytical purposes
  62. Analysis of different substances. Analytical control in production conditions
  63. Analysis, investigation and handling in general
  64. Analytical chemistry
  65. Analytical palaeontology
  66. Anatomy. Human and comparative anatomy
  67. Ancient China and Japan
  68. Ancient Egypt
  69. Ancient Egyptian religion
  70. Ancient Greece
  71. Ancient India
  72. Ancient Roman Province of Judaea. The Holy Land. Region of the Israelites
  73. Ancillary sciences of geology etc.
  74. Andean languages
  75. Andean languages. Equatorial languages
  76. Andorra. The Principality of Andorra. Principat d'Andorra
  77. Angiospermae (Magnoliophyta). Angiosperms. Flowering plants. Covered-seed plants. Later seed plants
  78. Angola. Republic of Angola
  79. Animal embryology. Animal ontogeny. Development of the individual organism
  80. Animal fibres
  81. Animal habits. Animal behaviour. Ecology. Ethology. Animal and environment. Bionomy
  82. Animal health. Veterinary hygiene
  83. Animal heat. Thermal processes
  84. Animal histology
  85. Animal husbandry and breeding in general. Livestock rearing. Breeding of domestic animals
  86. Animal physiology
  87. Animals according to breeding
  88. Animals bred or kept for food or other produce (productivity, yield). Farm and ranch animals in general
  89. Animals bred or kept for work and service or pleasure of humans
  90. Animals kept for breeding, showing and scientific uses
  91. Antarctic territories. South Polar regions
  92. Anthropogeny. Human development in general. Origin of the human species
  93. Anura
  94. Apparatus and equipment for preparation, investigation and analysis
  95. Apparatus for production and study of phenomena
  96. Apparatus with wheel or motor mechanisms
  97. Application, utilization of phenomena
  98. Application-oriented computer-based techniques
  99. Applications of acoustics (theory)
  100. Applications of art (in industry, trade, the home, everyday life)
  101. Applications of biotechnology
  102. Applications of music in industry and trade, the home and everyday life
  103. Applications of optics in general
  104. Applied botany. Use of plants. Technobotany. Economic botany
  105. Applied geology and geophysics. Geological prospecting and exploration. Interpretation of results
  106. Applied graphic arts. Commercial graphics
  107. Applied linguistics
  108. Applied microbiology
  109. Applied psychology (psychotechnology) in general
  111. Applied, practical geography
  112. Arabian states and territories
  113. Arabic
  114. Araucanian languages
  115. Arch bridges
  116. Archaeological, prehistoric, protohistoric periods and ages
  117. Archaeology
  118. Archaeology. Prehistory. Cultural remains. Area studies
  119. Architectural details and finishes. Decoration. Ornament
  120. Architecture
  121. Archivistics. Archives (including public and other records)
  122. Arctic territories
  123. Area studies. Study of a locality
  124. Argentina. Argentine Republic. República Argentina
  125. Armaments. Ordnance. Arms. Weapons. Guns. Artillery. Small arms. Side arms. Armoured and other service vehicles. Ammunition and war gases. Guided missiles and rockets
  126. Armed forces generally. Armed services. Military life
  127. Armenia. Republic of Armenia. Hayastan. Hayastani Hanrapetut’yun (Haikakan Hanrapetoutioun)
  128. Armenian
  129. Armenian language
  130. Armenian literature
  131. Army service generally. Infantry. Foot soldiers
  132. Aromatic herbs. Plants for seasoning
  133. Aromatic plants. Condiment plants. Oleaginous plants. Dye plants. Tanning plants. Medicinal plants
  134. Art of movement. Dance
  135. Art of the ancient cultures of the Old World. Styles of Antiquity
  136. Art technique. Craftsmanship
  137. Articles in serials, collections etc. Contributions
  138. Articles of iron and steel in general
  139. Articles of nonferrous metals (except precious metals)
  140. Articles of precious metals, gems, precious stones
  141. Articulata
  142. Articulata
  143. Artificial furriery
  144. Artificial intelligence
  145. Artificial languages
  146. Artificial languages
  147. Artificial languages for use among human beings. International auxiliary languages (interlanguages)
  148. Artificial languages for use among human beings. International auxiliary languages (interlanguages)
  149. Artificial languages used to instruct machines. Programming languages. Computer languages
  150. Artillery
  151. Artillery. Engineers. Aviation. Various technical units and their function
  152. Artiodactyla (Even-toed ungulates)
  153. Artistic furniture, heating and lighting devices
  154. Artistic periods and phases. Schools, styles, influences
  155. Ascetics. Hermits. Fakirs
  156. Ashkenazi Judaism
  157. Asia
  158. Asian Continental Ancestry Group
  159. Assault and defence works. Siege works. Field fortifications. Trench works
  160. Asteridae
  161. Asteridae
  162. Astrometry. Spherical astronomy
  163. Astronomical instruments and techniques
  164. Astronomy. Astrophysics. Space research. Geodesy
  165. Attestations. Special-purpose documents
  166. Audio documents. Sound recordings
  167. Australia. Commonwealth of Australia
  168. Australian languages
  169. Austria. Republic of Austria. Republik Österreich
  170. Austro-Asiatic languages
  171. Austro-Asiatic languages. Austronesian languages
  172. Austro-Asiatic languages. Austronesian languages
  173. Austronesian languages
  174. Author bibliographies. Individual bibliographies
  175. Authorship. Literary activity and technique
  176. Automatic control technology. Smart technology
  177. Auxiliary legal sciences. Forensic psychology. Forensic chemistry. Forensic medicine
  178. Auxiliary sciences and studies of philology
  180. Aves (Birds)
  181. Aves. Fossil birds
  182. Awards. Honours. Prizes. Distribution of prizes, awards
  183. Aymara
  184. Azerbaijan. Azerbaijani Republic. Azərbaycan Respublikası
  185. Azerbaijani