| A - General Works | 274 | 0.01 |
| AC - Collections. Series. | 7,870 | 0.22 |
| AE - Encyclopedias | 732 | 0.02 |
| AG - Dictionaries and other reference | 574 | 0.02 |
| AI - Indexes | 290 | 0.01 |
| AM - Museums. Collectors and collecting | 1,294 | 0.04 |
| AN - Newspapers | 7 | 0.00 |
| AP - Periodicals | 4,435 | 0.12 |
| AS - Academies and learned societies | 5,862 | 0.16 |
| AY - Yearbooks. Almanacs. Directories | 642 | 0.02 |
| AZ - History of scholarship and learning | 760 | 0.02 |
| B - Philosophy; Psychology; Religion | 40,126 | 1.10 |
| BC - Logic | 2,251 | 0.06 |
| BD - Speculative philosophy | 6,493 | 0.18 |
| BF - Psychology | 24,712 | 0.68 |
| BH - Aesthetics | 2,086 | 0.06 |
| BJ - Ethics | 7,776 | 0.21 |
| BL - Religions. Mythology. Rationalism | 25,853 | 0.71 |
| BM - Judaism | 9,175 | 0.25 |
| BP - Islam. Bahaism. Theosophy | 17,516 | 0.48 |
| BQ - Buddhism | 7,835 | 0.22 |
| BR - Christianity | 16,877 | 0.46 |
| BS - The Bible | 16,256 | 0.45 |
| BT - Doctrinal Theology | 9,949 | 0.27 |
| BV - Practical Theology | 13,550 | 0.37 |
| BX - Christian Denominations | 44,620 | 1.22 |
| C - Auxiliary Science of History | 481 | 0.01 |
| CB - History of Civilization | 4,644 | 0.13 |
| CC - Archaeology | 1,638 | 0.04 |
| CD - Diplomatics. Archives. Seals | 4,242 | 0.12 |
| CE - Technical Chronology. Calendar | 483 | 0.01 |
| CJ - Numismatics | 2,228 | 0.06 |
| CN - Inscriptions. Epigraphy | 880 | 0.02 |
| CR - Heraldry | 1,696 | 0.05 |
| CS - Genealogy | 25,203 | 0.69 |
| CT - Biography | 8,568 | 0.24 |
| D - History General | 61,206 | 1.68 |
| DA - History of Great Britain - History of Ireland - History of the British Isles | 33,417 | 0.92 |
| DB - History of Austria - Liechtenstein - Hungary - Czechoslovakia | 11,968 | 0.33 |
| DC - History of France - Andorra - Monaco | 29,350 | 0.81 |
| DD - History of Germany | 28,625 | 0.79 |
| DE - History of the Greco-Roman World | 1,143 | 0.03 |
| DF - History of Greece | 6,442 | 0.18 |
| DG - History of Italy - Malta | 21,518 | 0.59 |
| DH - History of Low Countries - Benelux Countries | 2,115 | 0.06 |
| DJ - History of the Netherlands | 2,056 | 0.06 |
| DK - History of Russia; Soviet Union; Former Soviet Republics - History of Poland | 38,995 | 1.07 |
| DL - History of Northern Europe; Scandavia | 7,327 | 0.20 |
| DP - History of Spain - Portugal | 15,899 | 0.44 |
| DQ - History of Switzerland | 1,927 | 0.05 |
| DR - History of the Balkan Peninsula | 13,228 | 0.36 |
| DS - History of Asia | 133,969 | 3.68 |
| DT - History of Africa | 22,909 | 0.63 |
| DU - History of Oceania (South Seas) | 7,349 | 0.20 |
| DX - History of Gypsies | 394 | 0.01 |
| E - History of America | 78,494 | 2.15 |
| F - Local History of the United States and British; French; and Latin America | 197,730 | 5.43 |
| G - Geography; Anthropology; Recreation | 13,347 | 0.37 |
| GA - Mathematical geography; Cartography | 1,310 | 0.04 |
| GB - Physical geography | 7,554 | 0.21 |
| GC - Oceanography | 6,327 | 0.17 |
| GE - Environmental Sciences | 1,722 | 0.05 |
| GF - Human ecology; Anthropogeography | 1,687 | 0.05 |
| GN - Anthropology | 15,099 | 0.41 |
| GR - Folklore | 10,843 | 0.30 |
| GT - Manners and customs (General) | 5,438 | 0.15 |
| GV - Recreation; Leisure | 14,176 | 0.39 |
| H - Social sciences (General) | 7,440 | 0.20 |
| HA - Statistics | 6,109 | 0.17 |
| HB - Economic theory; Demography | 27,877 | 0.77 |
| HC - Economic history and conditions | 63,895 | 1.75 |
| HD - Industries; Land use; Labor | 117,211 | 3.22 |
| HE - Transportation and communications | 15,273 | 0.42 |
| HF - Commerce | 38,260 | 1.05 |
| HG - Finance | 32,519 | 0.89 |
| HJ - Public Finance | 12,396 | 0.34 |
| HM - Sociology (General) | 11,091 | 0.30 |
| HN - Social history and conditions; Social problems; Social reform | 16,923 | 0.46 |
| HQ - The family; Marriage; Woman; Sexuality | 26,360 | 0.72 |
| HV - Social pathology; Social and public welfare ; Criminology | 33,124 | 0.91 |
| HX - Socialism. Communism. Anarchism | 13,649 | 0.37 |
| J - General legislative and executive papers | 4,989 | 0.14 |
| JA - Political science (General) | 4,453 | 0.12 |
| JC - Political theory. The state. Theories of the state. | 11,642 | 0.32 |
| JF - Political institutions and public administration - General | 3,660 | 0.10 |
| JJ - Political institutions and public administration - North America | 6 | 0.00 |
| JK - Political institutions and public administration - United States | 11,934 | 0.33 |
| JL - Political institutions and public administration - Canada; Latin America; etc. | 3,736 | 0.10 |
| JN - Political institutions and public administration - Europe | 16,487 | 0.45 |
| JQ - Political Institutions and public administration - Asia; Africa; Australia; Pacific Area; etc. | 13,493 | 0.37 |
| JS - Local government. Municipal government | 6,767 | 0.19 |
| JV - Colonies and colonization. Emigration and Immigration. International migration | 3,964 | 0.11 |
| JX - International law (obsolete) | 13,946 | 0.38 |
| JZ - International relations | 2,581 | 0.07 |
| K - Law | 9,964 | 0.27 |
| KB - Religious law | 1,037 | 0.03 |
| KDK - Law (United Kingdom and Ireland | 3,128 | 0.09 |
| KE - Law (Canada) | 856 | 0.02 |
| KF - Law (United States) | 39,336 | 1.08 |
| KG - Law (Latin America - Mexico and Central America - West Indies. Caribbean area) | 1,263 | 0.03 |
| KH - Law (South America) | 2,767 | 0.08 |
| KJ - Law (Europe) | 5,021 | 0.14 |
| KL - Law (History of law. The ancient orient) | 1,326 | 0.04 |
| KZ - Law of Nations. International law | 1,580 | 0.04 |
| L - Education | 4,052 | 0.11 |
| LA - History of Education | 14,686 | 0.40 |
| LB - Theory and practice of education | 37,310 | 1.02 |
| LC - Special aspects of education | 16,564 | 0.45 |
| LD - Education (Individual Institutions - United States) | 5,405 | 0.15 |
| LE - Education (Individual Institutions - America (except United States)) | 564 | 0.02 |
| LF - Education (Individual Institutions - Europe) | 2,988 | 0.08 |
| LG - Education (Individual Institutions - Asia; Africa; Indian Ocean Islands; Australia; New Zealand; Pacific Islands) | 1,494 | 0.04 |
| LH - College and school magazines and papers | 158 | 0.00 |
| LJ - Student fraternities; United States | 300 | 0.01 |
| LT - Textbooks | 204 | 0.01 |
| M - Printed Music | 42,997 | 1.18 |
| ML - Literature on music | 36,351 | 1.00 |
| MT - Musical instruction and study | 5,807 | 0.16 |
| N - Visual arts | 40,620 | 1.12 |
| NA - Architecture | 24,201 | 0.66 |
| NB - Sculpture | 7,447 | 0.20 |
| NC - Drawing. Design. Illustration | 7,001 | 0.19 |
| ND - Painting | 27,904 | 0.77 |
| NE - Print media | 4,072 | 0.11 |
| NK - Decorative arts | 14,081 | 0.39 |
| NX - Arts in general | 3,878 | 0.11 |
| P - Language and Literature | 18,659 | 0.51 |
| PA - Greek and Latin language and literature | 28,505 | 0.78 |
| PB - Modern languages; Celtic languages | 1,909 | 0.05 |
| PC - Romanic languages | 15,025 | 0.41 |
| PE - English language | 9,780 | 0.27 |
| PF - West Germanic languages | 6,456 | 0.18 |
| PG - Slavic languages; Baltic languages; Albanian language | 75,447 | 2.07 |
| PH - Uralic languages; Basque language | 7,894 | 0.22 |
| PJ - Oriental philology and literature | 29,197 | 0.80 |
| PK - Indo-Iranian philology and literature | 59,877 | 1.64 |
| PL - Languages of Eastern Asia; Africa; Oceania | 94,492 | 2.59 |
| PM - Hyperborean; Indian; and artificial languages | 1,957 | 0.05 |
| PN - Literature (General) | 69,642 | 1.91 |
| PQ - French literature - Italian literature - Spanish literature - Portuguese literature | 188,712 | 5.18 |
| PR - English literature | 87,852 | 2.41 |
| PS - American literature | 84,086 | 2.31 |
| PT - German; Dutch; Scandinavian; Old Norse; Old Icelandic; Old Norwegian; Modern Icelandic; Faroese; Danish; Norwegian; and Swedish literature; Flemish literature since 1830 | 106,212 | 2.92 |
| PZ - Fiction and juvenile belles lettres | 47,987 | 1.32 |
| Q - Science (General) | 17,408 | 0.48 |
| QA - Mathematics | 53,357 | 1.46 |
| QB - Astronomy | 11,408 | 0.31 |
| QC - Physics | 34,565 | 0.95 |
| QD - Chemistry | 20,126 | 0.55 |
| QE - Geology | 22,202 | 0.61 |
| QH - Natural history - Biology | 23,501 | 0.65 |
| QK - Botany | 16,561 | 0.45 |
| QL - Zoology | 28,815 | 0.79 |
| QM - Human anatomy | 2,627 | 0.07 |
| QP - Physiology | 17,069 | 0.47 |
| QR - Microbiology | 5,463 | 0.15 |
| R - Medicine (General) | 10,862 | 0.30 |
| RA - Public aspects of medicine | 15,827 | 0.43 |
| RB - Pathology | 3,177 | 0.09 |
| RC - Internal medicine | 37,340 | 1.03 |
| RD - Surgery | 7,327 | 0.20 |
| RE - Ophthalmology | 2,506 | 0.07 |
| RF - Otorhinolaryngology | 1,051 | 0.03 |
| RG - Gynecology and obstetrics | 3,781 | 0.10 |
| RJ - Pediatrics | 5,894 | 0.16 |
| RK - Dentistry | 3,415 | 0.09 |
| RL - Dermatology | 786 | 0.02 |
| RM - Therapeutics. Pharmacology | 5,830 | 0.16 |
| RS - Pharmacy and materia medica | 2,730 | 0.07 |
| RT - Nursing | 4,114 | 0.11 |
| RV - Botanic; Thomsonian; and eclectic medicine | 62 | 0.00 |
| RX - Homeopathy | 287 | 0.01 |
| RZ - Other systems of medicine | 332 | 0.01 |
| S - Agriculture (General) | 22,024 | 0.60 |
| SB - Plant culture | 25,367 | 0.70 |
| SD - Forestry | 9,273 | 0.25 |
| SF - Animal culture | 14,588 | 0.40 |
| SH - Aquaculture. Fisheries. Angling. | 8,065 | 0.22 |
| SK - Hunting sports | 3,216 | 0.09 |
| T - Technology (General) | 11,418 | 0.31 |
| TA - Engineering (General). Civil Engineering | 22,255 | 0.61 |
| TC - Hydraulic engineering - Ocean Engineering | 5,087 | 0.14 |
| TD - Environmental technology. Sanitary engineering | 10,198 | 0.28 |
| TE - Highway engineering. Roads and pavements | 1,427 | 0.04 |
| TF - Railroad engineering and operation | 1,891 | 0.05 |
| TG - Bridge engineering | 1,331 | 0.04 |
| TH - Building construction | 5,520 | 0.15 |
| TJ - Mechanical engineering and machinery | 11,126 | 0.31 |
| TK - Electrical engineering. Electronics. Nuclear engineering | 22,675 | 0.62 |
| TL - Motor vehicles. Aeronautics. Astronautics | 15,839 | 0.43 |
| TN - Mining engineering. Metallurgy | 12,124 | 0.33 |
| TP - Chemical technology | 12,771 | 0.35 |
| TR - Photography | 8,293 | 0.23 |
| TS - Manufactures | 9,649 | 0.26 |
| TT - Handicrafts. Arts and crafts | 3,676 | 0.10 |
| TX - Home economics | 11,150 | 0.31 |
| U - Military Science (General) | 5,268 | 0.14 |
| UA - Armies: Organization; distribution; military situation | 7,959 | 0.22 |
| UB - Military administration | 2,605 | 0.07 |
| UC - Maintenance and transportation | 757 | 0.02 |
| UD - Infantry | 257 | 0.01 |
| UE - Cavalry. Armor | 146 | 0.00 |
| UF - Artillery | 917 | 0.03 |
| UG - Military engineering | 2,599 | 0.07 |
| UH - Other services | 454 | 0.01 |
| V - Naval science (General) | 1,403 | 0.04 |
| VA - Navies: Organization; distribution; naval situation | 1,105 | 0.03 |
| VB - Naval administration | 213 | 0.01 |
| VC - Naval maintenance | 116 | 0.00 |
| VD - Naval seaman | 12 | 0.00 |
| VE - Marines | 144 | 0.00 |
| VF - Naval ordnance | 377 | 0.01 |
| VG - Minor services of navies | 339 | 0.01 |
| VK - Navigation. Merchant marine | 2,038 | 0.06 |
| VM - Naval architecture. Shipbuilding. Marine engineering | 2,535 | 0.07 |
| Z - Books (General). Writing. Paleography. Book industries and trade. Libraries. Bibliography | 74,128 | 2.04 |
| ZA - Information Resources | 282 | 0.01 |