| A (General Works) |
| AC |
Collections, series, collected works |
| AE |
Encyclopedias (general) |
| AI |
Indexes (general) |
| AM |
Museums (general), collectors and collecting |
| AN |
Newspapers |
| AP |
Periodicals |
| AS |
Academies and learned societies (general) |
| AY |
Yearbooks, almanacs, directories |
| AZ |
History of scholarship and learning |
| B (Philosophy, psychology, religion) |
| BF |
Psychology |
| BJ |
Ethics, social usages, etiquette |
| BL |
Religions, mythology, rationalism |
| BM |
Judaism |
| BP |
Islam, Bahaism, theosophy |
| BQ |
Buddhism |
| BR |
Christianity |
| BS |
Bible |
| BT |
Doctrinal theology |
| BT |
Practical theology |
| BX |
Christian Denominations |
| C (Auxiliary sciences of history) |
| CC |
Archaeology (general) |
| CD |
Diplomatics, archives, seals |
| CE |
Technical chronology, calendars |
| CJ |
Numismatics |
| CN |
Inscriptions, epigraphy |
| CR |
Heraldry |
| CS |
Geneology |
| CT |
Biography (general) |
| D (History: General and Old World) |
| D |
History (general) |
| DA |
Great Britain |
| DB |
Austria, Liechtenstein, Hungary, Czechoslovakia |
| DC |
France |
| DD |
Germany |
| DE |
The Mediterranean region, the Greco-Roman world |
| DF |
Greece |
| DG |
Italy |
| DJ |
Holland |
| DL |
Scandinavia |
| DP |
Spain, Portugal |
| DQ |
Switzerland |
| DR |
Balkan Peninsula |
| DS |
Asia |
| DT |
Africa |
| DU |
Australia, Oceania |
| DX |
Gypsies |
| E (History: United States (general) including Native Americans) |
| E |
History: United States |
| F (History: U.S. Local, Canada, Mexico, Central and South America) |
| G (Geography, anthropology, recreation) |
| G |
Geography (general), atlases, maps |
| GA |
Mathematical geography, cartography |
| GB |
Physical geography |
| GC |
Oceanography |
| GE |
Environmental education |
| GN |
Anthropology |
| GR |
Folklore, manners and customs |
| GV |
Recreation, sports, leisure |
| H (Social Sciences) |
| H |
Social Sciences (general) |
| HA |
Statistics |
| HB |
Economic theory, demography |
| HC |
Economic history and conditions |
| HD |
Production, agriculture, labor |
| HE |
Transportation, communications |
| HF |
Commerce, accounting |
| HG-HJ |
Finance |
| HM |
Sociology |
| HN |
Social history, social problems, social reform |
| HQ |
The family, marriage, women |
| HS |
Societies (secret, benevolent), clubs |
| HT |
Communities, classes, races |
| HV |
Social pathology, social and public welfare, criminology |
| HX |
Socialism, communism, anarchism |
| J (Political science) |
| JC |
Human Rights |
| JK |
United States government |
| JL-JQ |
Foreign governments |
| JS |
Local government |
| JV |
Colonies and colonization, emigration and immigration |
| JX |
International law and international relations |
| K |
(Law) |
| K |
Law (general) |
| KD |
Law of the United Kingdom and Ireland |
| KE |
Law of Canada |
| KF |
Law of the United States |
| KG |
Latin America |
| KH |
South America (general) |
| KJ |
Europe |
| KK-KZ |
Other countries |
| L (Education) |
| L |
Education (general) |
| LA |
History of education |
| LB |
Theory and practice of education |
| LC |
Special aspects of education |
| LD |
United States |
| LE |
America, except United States |
| LF |
Europe |
| LG |
Asia, Africa, Oceania |
| LH |
College and school magazines and papers |
| LJ |
Student fraternities and socieites, U.S. |
| LT |
Textbooks |
| M (Music) |
| M |
Music |
| ML |
Literature of music |
| MT |
Musical instruction and study |
| N (Fine Arts) |
| N |
Visual arts (general) |
| NA |
Archictecture |
| NB |
Sculpture |
| NC |
Drawing, design, illustration |
| ND |
Painting |
| NE |
Print media |
| NK |
Decorative arts, applied arts, antiques, other arts |
| NX |
Arts in general |
| P (Language and Literature) |
| P |
Philology and Linguistics |
| PA |
Classical languages and literature |
| PB |
General European languages, Celtic language and literature |
| PB |
(Language and Literature) |
| PC |
Romance languages |
| PD |
Old Germanic, Scandinavian |
| PE |
English |
| PF |
Dutch, Flemish, Frisian, German |
| PG |
Slavic, Baltic, Albanian |
| PH |
Finno-Ugrian, Basque |
| PJ |
Egyptian, Libyan Berber, Cushitic, Semitic languages |
| PL |
East African, African, Oceanic languages |
| PM |
Hyperborean, Indian, and artificial languages |
| PN |
Literary history and collections, drama, journalism, collections |
| PQ |
Romance literatures |
| PR |
English literature |
| PS |
American Literature |
| PT |
Germanic literatures |
| PZ |
Juvenile belles lettres, miscellaneous literature |
| Q (Science) |
| Q |
Science (general), information theory |
| QA |
Mathematics |
| QB |
Astronomy |
| QC |
Physics |
| QD |
Chemistry |
| QE |
Geology |
| QH |
Natural history, biology |
| QK |
Botany |
| QL |
Zoology |
| QM |
Human Anatomy |
| QP |
Physiology |
| QR |
Microbiology |
| R (Medicine) |
| R |
Medicine (general) |
| RA |
Public aspects of medicine |
| RB |
Pathology |
| RC |
Internal medicine, medical practice |
| RD |
Surgery |
| RE |
Ophthalmology |
| RF |
Otorhinolaryngology |
| RG |
Gynecology and obstetrics |
| RJ |
Pediatrics |
| RK |
Dentistry |
| RL |
Dermatology |
| RM |
Therapeutics, pharmacology |
| RS |
Pharmacy and materia medica |
| RT |
Nursing |
| RV |
Eclectic medicine |
| RX |
Homeopathy |
| RZ |
Other systems of medicine |
| S (Agriculture) |
| SB |
Plant culture |
| SD |
Forestry |
| SF |
Animal culture |
| SH |
Aquaculture, fisheries, angling |
| SK |
Hunting, wildlife management |
| T (Technology) |
| T |
Technology (general) |
| TA |
Engineering (general), civil engineering (general) |
| TC |
Hydraulic engineering |
| TD |
Environmental technology, sanitary engineering |
| TE |
Highway engineering, roads and pavements |
| TF |
Bridge Construction |
| TH |
Building construction |
| TF |
Railroad engineering and operation |
| TJ |
Mechanical engineering and machinery |
| TK |
Electrical engineering, electronics (Internet) |
| TL |
Motor vehicles, aeronautics, UFOs |
| TN |
Mining, metallurgy |
| TP |
Chemical technology |
| TR |
Photography |
| TS |
Manufactures |
| TT |
Handicrafts, arts, and crafts |
| TX |
Home Economics |
| U (Military science) |
| U-UH |
Military science |
| V |
(Naval science) |
| V-VM |
Naval science |
| Z (Bibliography, library science) |
| Z |
History of books, booktrade, libraries, bibliography |
