| A - General Works | 97 | 0.01 |
| AC - Collections. Series. | 1,466 | 0.19 |
| AE - Encyclopedias | 261 | 0.03 |
| AG - Dictionaries and other reference | 238 | 0.03 |
| AI - Indexes | 67 | 0.01 |
| AM - Museums. Collectors and collecting | 194 | 0.03 |
| AN - Newspapers | 4 | 0.00 |
| AP - Periodicals | 2,147 | 0.28 |
| AS - Academies and learned societies | 1,403 | 0.18 |
| AY - Yearbooks. Almanacs. Directories | 453 | 0.06 |
| AZ - History of scholarship and learning | 78 | 0.01 |
| B - Philosophy; Psychology; Religion | 6,681 | 0.87 |
| BC - Logic | 536 | 0.07 |
| BD - Speculative philosophy | 1,192 | 0.16 |
| BF - Psychology | 4,926 | 0.64 |
| BH - Aesthetics | 256 | 0.03 |
| BJ - Ethics | 2,300 | 0.30 |
| BL - Religions. Mythology. Rationalism | 3,453 | 0.45 |
| BM - Judaism | 1,467 | 0.19 |
| BP - Islam. Bahaism. Theosophy | 679 | 0.09 |
| BQ - Buddhism | 106 | 0.01 |
| BR - Christianity | 5,133 | 0.67 |
| BS - The Bible | 6,523 | 0.85 |
| BT - Doctrinal Theology | 3,942 | 0.52 |
| BV - Practical Theology | 6,148 | 0.80 |
| BX - Christian Denominations | 16,367 | 2.14 |
| C - Auxiliary Science of History | 441 | 0.06 |
| CB - History of Civilization | 626 | 0.08 |
| CC - Archaeology | 146 | 0.02 |
| CD - Diplomatics. Archives. Seals | 807 | 0.11 |
| CE - Technical Chronology. Calendar | 152 | 0.02 |
| CJ - Numismatics | 533 | 0.07 |
| CN - Inscriptions. Epigraphy | 134 | 0.02 |
| CR - Heraldry | 535 | 0.07 |
| CS - Genealogy | 6,090 | 0.80 |
| CT - Biography | 1,908 | 0.25 |
| D - History General | 16,605 | 2.17 |
| DA - History of Great Britain - History of Ireland - History of the British Isles | 13,120 | 1.72 |
| DB - History of Austria - Liechtenstein - Hungary - Czechoslovakia | 2,175 | 0.28 |
| DC - History of France - Andorra - Monaco | 11,144 | 1.46 |
| DD - History of Germany | 5,552 | 0.73 |
| DE - History of the Greco-Roman World | 340 | 0.04 |
| DF - History of Greece | 1,646 | 0.22 |
| DG - History of Italy - Malta | 6,560 | 0.86 |
| DH - History of Low Countries - Benelux Countries | 743 | 0.10 |
| DJ - History of the Netherlands | 473 | 0.06 |
| DK - History of Russia; Soviet Union; Former Soviet Republics - History of Poland | 5,329 | 0.70 |
| DL - History of Northern Europe; Scandavia | 1,431 | 0.19 |
| DP - History of Spain - Portugal | 2,669 | 0.35 |
| DQ - History of Switzerland | 692 | 0.09 |
| DR - History of the Balkan Peninsula | 1,632 | 0.21 |
| DS - History of Asia | 10,538 | 1.38 |
| DT - History of Africa | 4,432 | 0.58 |
| DU - History of Oceania (South Seas) | 1,564 | 0.20 |
| DX - History of Gypsies | 74 | 0.01 |
| E - History of America | 35,735 | 4.68 |
| F - Local History of the United States and British; French; and Latin America | 59,982 | 7.85 |
| G - Geography; Anthropology; Recreation | 4,204 | 0.55 |
| GA - Mathematical geography; Cartography | 242 | 0.03 |
| GB - Physical geography | 2,812 | 0.37 |
| GC - Oceanography | 977 | 0.13 |
| GE - Environmental Sciences | 38 | 0.00 |
| GF - Human ecology; Anthropogeography | 91 | 0.01 |
| GN - Anthropology | 1,820 | 0.24 |
| GR - Folklore | 1,588 | 0.21 |
| GT - Manners and customs (General) | 445 | 0.06 |
| GV - Recreation; Leisure | 3,132 | 0.41 |
| H - Social sciences (General) | 935 | 0.12 |
| HA - Statistics | 1,507 | 0.20 |
| HB - Economic theory; Demography | 4,130 | 0.54 |
| HC - Economic history and conditions | 4,753 | 0.62 |
| HD - Industries; Land use; Labor | 18,173 | 2.38 |
| HE - Transportation and communications | 5,222 | 0.68 |
| HF - Commerce | 7,851 | 1.03 |
| HG - Finance | 5,674 | 0.74 |
| HJ - Public Finance | 4,197 | 0.55 |
| HM - Sociology (General) | 1,033 | 0.14 |
| HN - Social history and conditions; Social problems; Social reform | 1,339 | 0.18 |
| HQ - The family; Marriage; Woman; Sexuality | 2,670 | 0.35 |
| HV - Social pathology; Social and public welfare ; Criminology | 7,475 | 0.98 |
| HX - Socialism. Communism. Anarchism | 1,788 | 0.23 |
| J - General legislative and executive papers | 2,623 | 0.34 |
| JA - Political science (General) | 365 | 0.05 |
| JC - Political theory. The state. Theories of the state. | 1,784 | 0.23 |
| JF - Political institutions and public administration - General | 663 | 0.09 |
| JK - Political institutions and public administration - United States | 5,424 | 0.71 |
| JL - Political institutions and public administration - Canada; Latin America; etc. | 470 | 0.06 |
| JN - Political institutions and public administration - Europe | 2,559 | 0.33 |
| JQ - Political Institutions and public administration - Asia; Africa; Australia; Pacific Area; etc. | 357 | 0.05 |
| JS - Local government. Municipal government | 1,450 | 0.19 |
| JV - Colonies and colonization. Emigration and Immigration. International migration | 829 | 0.11 |
| JX - International law (obsolete) | 3,257 | 0.43 |
| JZ - International relations | 365 | 0.05 |
| K - Law | 2,300 | 0.30 |
| KB - Religious law | 205 | 0.03 |
| KDK - Law (United Kingdom and Ireland | 1,499 | 0.20 |
| KE - Law (Canada) | 282 | 0.04 |
| KF - Law (United States) | 23,631 | 3.09 |
| KG - Law (Latin America - Mexico and Central America - West Indies. Caribbean area) | 548 | 0.07 |
| KH - Law (South America) | 546 | 0.07 |
| KJ - Law (Europe) | 1,378 | 0.18 |
| KL - Law (History of law. The ancient orient) | 65 | 0.01 |
| KZ - Law of Nations. International law | 705 | 0.09 |
| L - Education | 1,707 | 0.22 |
| LA - History of Education | 2,695 | 0.35 |
| LB - Theory and practice of education | 10,258 | 1.34 |
| LC - Special aspects of education | 3,024 | 0.40 |
| LD - Education (Individual Institutions - United States) | 2,907 | 0.38 |
| LE - Education (Individual Institutions - America (except United States)) | 86 | 0.01 |
| LF - Education (Individual Institutions - Europe) | 999 | 0.13 |
| LG - Education (Individual Institutions - Asia; Africa; Indian Ocean Islands; Australia; New Zealand; Pacific Islands) | 65 | 0.01 |
| LH - College and school magazines and papers | 73 | 0.01 |
| LJ - Student fraternities; United States | 236 | 0.03 |
| LT - Textbooks | 37 | 0.00 |
| M - Printed Music | 3,260 | 0.43 |
| ML - Literature on music | 4,572 | 0.60 |
| MT - Musical instruction and study | 1,189 | 0.16 |
| N - Visual arts | 4,035 | 0.53 |
| NA - Architecture | 2,880 | 0.38 |
| NB - Sculpture | 719 | 0.09 |
| NC - Drawing. Design. Illustration | 670 | 0.09 |
| ND - Painting | 2,721 | 0.36 |
| NE - Print media | 677 | 0.09 |
| NK - Decorative arts | 1,585 | 0.21 |
| NX - Arts in general | 81 | 0.01 |
| P - Language and Literature | 890 | 0.12 |
| PA - Greek and Latin language and literature | 12,176 | 1.59 |
| PB - Modern languages; Celtic languages | 602 | 0.08 |
| PC - Romanic languages | 2,602 | 0.34 |
| PE - English language | 3,025 | 0.40 |
| PF - West Germanic languages | 1,942 | 0.25 |
| PG - Slavic languages; Baltic languages; Albanian language | 5,295 | 0.69 |
| PH - Uralic languages; Basque language | 552 | 0.07 |
| PJ - Oriental philology and literature | 2,156 | 0.28 |
| PK - Indo-Iranian philology and literature | 1,233 | 0.16 |
| PL - Languages of Eastern Asia; Africa; Oceania | 2,014 | 0.26 |
| PM - Hyperborean; Indian; and artificial languages | 402 | 0.05 |
| PN - Literature (General) | 7,875 | 1.03 |
| PQ - French literature - Italian literature - Spanish literature - Portuguese literature | 24,708 | 3.23 |
| PR - English literature | 28,636 | 3.75 |
| PS - American literature | 26,935 | 3.52 |
| PT - German; Dutch; Scandinavian; Old Norse; Old Icelandic; Old Norwegian; Modern Icelandic; Faroese; Danish; Norwegian; and Swedish literature; Flemish literature since 1830 | 18,289 | 2.39 |
| PZ - Fiction and juvenile belles lettres | 20,154 | 2.64 |
| Q - Science (General) | 3,989 | 0.52 |
| QA - Mathematics | 7,245 | 0.95 |
| QB - Astronomy | 3,168 | 0.41 |
| QC - Physics | 7,934 | 1.04 |
| QD - Chemistry | 4,298 | 0.56 |
| QE - Geology | 4,993 | 0.65 |
| QH - Natural history - Biology | 4,820 | 0.63 |
| QK - Botany | 4,299 | 0.56 |
| QL - Zoology | 7,329 | 0.96 |
| QM - Human anatomy | 861 | 0.11 |
| QP - Physiology | 2,704 | 0.35 |
| QR - Microbiology | 903 | 0.12 |
| R - Medicine (General) | 1,730 | 0.23 |
| RA - Public aspects of medicine | 3,678 | 0.48 |
| RB - Pathology | 564 | 0.07 |
| RC - Internal medicine | 5,240 | 0.69 |
| RD - Surgery | 1,031 | 0.13 |
| RE - Ophthalmology | 551 | 0.07 |
| RF - Otorhinolaryngology | 206 | 0.03 |
| RG - Gynecology and obstetrics | 602 | 0.08 |
| RJ - Pediatrics | 617 | 0.08 |
| RK - Dentistry | 622 | 0.08 |
| RL - Dermatology | 221 | 0.03 |
| RM - Therapeutics. Pharmacology | 1,174 | 0.15 |
| RS - Pharmacy and materia medica | 672 | 0.09 |
| RT - Nursing | 238 | 0.03 |
| RV - Botanic; Thomsonian; and eclectic medicine | 57 | 0.01 |
| RX - Homeopathy | 220 | 0.03 |
| RZ - Other systems of medicine | 127 | 0.02 |
| S - Agriculture (General) | 7,202 | 0.94 |
| SB - Plant culture | 7,004 | 0.92 |
| SD - Forestry | 4,023 | 0.53 |
| SF - Animal culture | 5,548 | 0.73 |
| SH - Aquaculture. Fisheries. Angling. | 2,346 | 0.31 |
| SK - Hunting sports | 1,716 | 0.22 |
| T - Technology (General) | 2,784 | 0.36 |
| TA - Engineering (General). Civil Engineering | 2,848 | 0.37 |
| TC - Hydraulic engineering - Ocean Engineering | 1,908 | 0.25 |
| TD - Environmental technology. Sanitary engineering | 2,343 | 0.31 |
| TE - Highway engineering. Roads and pavements | 507 | 0.07 |
| TF - Railroad engineering and operation | 936 | 0.12 |
| TG - Bridge engineering | 566 | 0.07 |
| TH - Building construction | 1,502 | 0.20 |
| TJ - Mechanical engineering and machinery | 2,784 | 0.36 |
| TK - Electrical engineering. Electronics. Nuclear engineering | 2,828 | 0.37 |
| TL - Motor vehicles. Aeronautics. Astronautics | 7,693 | 1.01 |
| TN - Mining engineering. Metallurgy | 3,857 | 0.50 |
| TP - Chemical technology | 3,057 | 0.40 |
| TR - Photography | 578 | 0.08 |
| TS - Manufactures | 2,566 | 0.34 |
| TT - Handicrafts. Arts and crafts | 1,277 | 0.17 |
| TX - Home economics | 3,987 | 0.52 |
| U - Military Science (General) | 1,461 | 0.19 |
| UA - Armies: Organization; distribution; military situation | 1,573 | 0.21 |
| UB - Military administration | 1,079 | 0.14 |
| UC - Maintenance and transportation | 401 | 0.05 |
| UD - Infantry | 176 | 0.02 |
| UE - Cavalry. Armor | 85 | 0.01 |
| UF - Artillery | 468 | 0.06 |
| UG - Military engineering | 811 | 0.11 |
| UH - Other services | 247 | 0.03 |
| V - Naval science (General) | 475 | 0.06 |
| VA - Navies: Organization; distribution; naval situation | 277 | 0.04 |
| VB - Naval administration | 106 | 0.01 |
| VC - Naval maintenance | 87 | 0.01 |
| VD - Naval seaman | 11 | 0.00 |
| VE - Marines | 60 | 0.01 |
| VF - Naval ordnance | 139 | 0.02 |
| VG - Minor services of navies | 207 | 0.03 |
| VK - Navigation. Merchant marine | 946 | 0.12 |
| VM - Naval architecture. Shipbuilding. Marine engineering | 783 | 0.10 |
| Z - Books (General). Writing. Paleography. Book industries and trade. Libraries. Bibliography | 16,917 | 2.21 |
| ZA - Information Resources | 8 | 0.00 |