Major Library of Congress Classifications
| A | General Works | |
| AE | Encyclopedias | |
| B-BD | Philosophy | |
| BF | Psychology, Behavioral | |
| BH-BJ | Philosophy | |
| BJ | Religion | |
| BL-BX | Theater | |
| C | History of Civilization | |
| CT | Biography | |
| D | General History | |
| DA | Great Britain | |
| DB-DR | Europe | |
| DS-DT | Asia, Africa, Middle East | |
| DU | Australia, Oceania | |
| E-F | History of the Americas | |
| F | Canada, Latin America | |
| G-GC | Geography | |
| GF-GT | Anthropology | |
| GV | Sports | |
| H | Social Sciences, General | |
| HB-HC | Business; Economics | |
| HD | Management | |
| HF | Accounting; Marketing | |
| HG | Finance; Women's Studies | |
| HM-HX | Sociology | |
| HQ | Child/Family Studies | |
| HV | Criminology; Human Sciences | |
| J | Political Science | |
| K | Law | |
| L-LJ | Education | |
| LB, BF | Counseling; Health (LB) | |
| LB | Elementary Education | |
| LC | Special Education | |
| M | Music | |
| N | Art and Architecture | |
| O | ||
| P | Language and Literature | |
| PA | Classics, Language and Literature | |
| PB-PH | Modern European Languages | |
| PC | Spanish Language | |
| PG | French Language and Literature | |
| PJ-PL | Asian Language and Literature | |
| PN | General Literature; Communications and Speech; Drama; Film | |
| PQ | Spanish Literature | |
| PS | American Literature | |
| PT | German, Dutch, Scandinavian Literature | |
| Q | Science | |
| QA76 | Computer Science | |
| QB | Astronomy | |
| QC | Physics | |
| QD | Chemistry; Biochemistry | |
| QE | Geology | |
| QH-QR | Biology; Biophysics; Ecology; Microbiology; Hearing/Speech | |
| R | Medicine | |
| RC | Hearing and Speech; Clinical Psychology | |
| RF | Hearing and Speech | |
| RT | Nursing | |
| S | Agriculture | |
| T | Technology | |
| TA | Engineering | |
| TD-TJ | Environmental Science | |
| TK | Computer Science | |
| TR | Photography | |
| TS | Industrial Technology | |
| TX | Home Economics; Food and Nutrition | |
| U | Military Science | |
| V | Naval Science | |
| Z | Bibliography; Library Science; General Information Sources |