Thema – the subject category scheme for a global book trade

  1. Oahu
  2. Oaxaca
  3. Oaxaca de Juarez
  4. Obesity: treatment & therapy
  5. Object oriented software engineering
  6. Object-oriented databases
  7. Object-oriented programming (OOP)
  8. Obwalden / Obwald / Obvaldo / Sursilvania
  9. Occidental
  10. Occitan (lenga d’òc)
  11. Occitanie
  12. Occitanie: Places of interest
  13. Occult fiction
  14. Occult studies
  15. Occupational & industrial psychology
  16. Occupational health & safety law, working time law
  17. Occupational medicine
  18. Occupational therapy
  19. Oceania
  20. Oceanic & Austronesian languages
  21. Oceanic & Polynesian languages
  22. Oceanography (seas & oceans)
  23. Oceans & seas
  24. OCR – Oxford, Cambridge and RSA Examinations
  25. Odense
  26. Oder and Neisse rivers & tributaries
  27. Odisha
  28. Offaly
  29. Offences against land use & city planning, monument, land & environment protection
  30. Offences against public health, safety, order
  31. Offences against the State, against public administration & the administration of justice
  32. Offenders
  33. Office & workplace
  34. Office management
  35. Office systems & equipment
  36. Ohio
  37. Oise
  38. Oita
  39. Ojibway
  40. Okavango River & Delta
  41. Okayama
  42. Okinawa
  43. Oklahoma
  44. Oklahoma City
  45. Öland
  46. Olbia Tempio
  47. Old Norse
  48. Old Testaments
  49. Olomouc Region
  50. Oloron-Sainte-Marie
  51. Olympic & Paralympic games
  52. Olympic National Park
  53. Omaha
  54. Oman
  55. Oncology
  56. Online finance & investing
  57. Online safety & behaviour
  58. Online shopping & auctions
  59. Ontario
  60. Op art
  61. OPEC
  62. Open learning, distance education
  63. Open source & other operating systems
  64. Opera
  65. Operating systems
  66. Operational research
  67. Ophthalmology
  68. Oppland
  69. Optical physics
  70. Optimization
  71. Optometry / opticians
  72. Oral & maxillofacial surgery
  73. Oral history
  74. Orange
  75. Ordnance, weapons technology
  76. Örebro
  77. Oregon
  78. Orense (City)
  79. Orense (Province)
  80. Organic chemistry
  81. Organic farming
  82. Organic food / organic cookery
  83. Organic gardening
  84. Organizational theory & behaviour
  85. Organized crime
  86. Organometallic chemistry
  87. Orientalism
  88. Orienteering
  89. Origami & paper engineering
  90. Orinoco River
  91. Oristano
  92. Orkney Islands
  93. Orlando
  94. Orléans
  95. Orleans Island
  96. Orne
  97. Oromo
  98. Orphism
  99. Orthodox & Oriental Orthodox Churches
  100. Orthodox Judaism
  101. Orthotics
  102. Oruro
  103. Osaka
  104. Oslo
  105. Oslofjorden
  106. Östergötland
  107. Österlen
  108. Östersund
  109. Other African languages
  110. Other entities in the Solar System
  111. Other geographical groupings: Oceans & seas, historical, political etc
  112. Other Germanic languages & dialects
  113. Other graphic art forms
  114. Other Greek Islands
  115. Other Indo-European languages
  116. Other languages
  117. Other manufacturing technologies
  118. Other Nonconformist & Evangelical Churches
  119. Other Oceanic languages
  120. Other performing arts
  121. Other Southeast Asian languages, Austroasiatic languages
  122. Other sports & competitive activities
  123. Other technologies & applied sciences
  124. Other transaction taxes
  125. Other vocational technologies & trades
  126. Other warfare & defence issues
  127. Other World religions
  128. OtjiHerero (Herero)
  129. Otorhinolaryngology (ENT)
  130. Ottoman Empire
  131. Ouarzazate
  132. Outdoor & recreational areas: design & maintenance
  133. Outdoor schools / education
  134. Outdoor survival skills
  135. Outer Banks
  136. Outsider art, Art brut
  137. Outsourcing
  138. Outsourcing law
  139. Overijssel
  140. Oviedo
  141. Ownership & mortgage law
  142. Ownership & organization of enterprises
  143. Oxford
  144. Oxfordshire