A. General Works
- AC. Collections, Series, Collected Works
- AE. Encyclopedias (General)
- AG. Dictionaries and Other General Reference Works
- AI. Indexes
- AM. Museums, Collectors and Collecting
- AN. Newspapers
- AP. Periodicals
- AS. Academies and Learned Societies
- AY. Yearbooks, Almanacs, Directories
- AZ. History of Scholarship and Learning
B. Philosophy, Psychology, and Religion
- B. History and Systems of Philosophy
- BC. Logic
- BD. Metaphysics, Speculative Philosophy
- BF. Psychology
- BH. Aesthetics
- BJ. Ethics
- BL. Religions, Mythology, Rationalism
- BM. Judaism
- BP. Islam, Baha'ism, Theosophy
- BQ. Buddhism
- BR-BX. Christianity
C. Auxiliary Sciences of History
- C. Auxiliary Sciences of History (General)
- CB. History of Civilization (General)
- CC. Archaeology
- CD. Diplomatics, Archives
- CE. Technical Chronology, Calendars
- CJ. Numismatics
- CN. Inscriptions, Epigraphy
- CR. Heraldry
- CS. Genealogy
- CT. Biography
D. History: General and Old World
- D. History (General)
- DA. Great Britain
- DAW. Central Europe
- DB. Austria, Liechtenstein, Hungary, Czech Republic
- DC. France, Andorra, Monaco
- DD. Germany
- DE. Mediterranean Region
- DF. Greece
- DG. Italy, Malta
- DH-DJ. Low Countries, Benelux Countries, Netherlands
- DJK. Eastern Europe (General)
- DK. Russia, Soviet Union, Former Soviet Republics, Poland
- DP. Spain, Portugal
- DQ. Switzerland
- DR. Balkan Peninsula
- DS. Asia
- DT. Africa
- DU. Oceania (South Seas)
- DX. Romanies
E. History: Americas (General)
- E11-143. America (General)
- E151-185.98. United States (General)
- E186-199. Colonial History (1607-1775)
- E201-298. The Revolution (1775-1783)
- E300-453. Revolution to the Civil War (1783-1861)
- E456-655. Civil War Period (1861-1865)
- E660-738. Late Nineteenth Century (1865-1900)
- E740-837.7. Twentieth Century (1900-1961)
- E838-889. Later Twentieth Century (1961-2000)
- E895-904. Twenty-First Century
F. History: Americas (Local)
- F. United States Local History
- F1-105. New England
- F106-205. Atlantic Coast, Middle Atlantic States
- F206-295. The South, South Atlantic States
- F251-265. North Carolina
- F296-395. Gulf States
- F396-475. Old Southwest, Lower Mississippi Valley
- F476-590. Old Northwest, Northwest Territory
- F590.3-705. The West, Trans-Mississippi Region, Great Plains
- F721-785. Rocky Mountains, Yellowstone National Park
- F786-850. New Southwest, Colorado River, Canyon, and Valley
- F850.5-951. Pacific States
- F965-975. Territories and Insular Possessions of the United States
- F10001-1145.2 British America (including Canada), Dutch America
- F1170. French America
- F1201-3799. Latin America, Spanish America
G. Geography and Anthropology
- G. Geography (General), Atlases, Maps
- GA. Mathematical Geography, Cartography
- GB. Physical Geography
- GC. Oceanography
- DG. Environmental Sciences
- GF. Human Ecology, Anthropogeography
- GN. Anthropology
- GR. Folklore
- GT. Manners and Customs
- GV. Recreation and Leisure
H. Social Sciences and Business
- H. Social Sciences (General)
- HA. Statistics
- HB. Economic Theory
- HC. Economic History and Conditions
- HD. Industries, Land Use, Labor
- HE. Transportation and Communication
- HF. Commerce
- HG-HJ. Finance
- HM. Sociology (General)
- HN. Social History and Conditions, Social Problems, Social Reform
- HQ. The Family, Marriage, Women
- HS. Societies: Secret, Benevolent, etc.
- HT. Communities, Classes, Races
- HV. Social Pathology, Social and Public Welfare, Criminology
- H. Socialism, Communism, Anarchism
J. Political Science
- J. General Legislative and Executive Papers
- JA. Political Science (General)
- JC. Political Theory
- JF-JQ. Political Institutions and Public Administration
- JS. Local Government and Municipal Government
- JV. Colonies and Colonization, Emigration and Immigration, Internal Migration
- JZ. International Relations
K. Law
- K. Law in General, Comparative and Uniform Law, Jurisprudence
- KB. Religious Law in General, Comparative Religious Law, Jurisprudence
- KBM. Jewish Law
- KBP. Islamic Law
- KBR. History of Canon Law
- KBU. Law of the Roman Catholic Church, The Holy See
- KD-KDK. America, North America
- KE. Canada
- KF. United States
- KG. Latin America, Mexico and Central America, West Indies, Caribbean Area
- KH. South America
- KJ-KKZ. Europe
- KL-KWX. Asia and Eurasia, Africa, Pacific Area, and Antarctica
- KZ. Law of Nations
L. Education
- L. Education (General)
- LA. History of Education
- LB. Theory and Practice of Education
- LC. Special Aspects of Education
- LD-LG. Individual Institutions
- LH. College and School Magazines and Papers
- LJ. Student Fraternities and Societies: Unites States
- LT. Textbooks
M. Music
- M. Music
- ML. Literature on Music
- MT. Instruction and Study
N. Fine Arts
- N. Visual Arts
- NA. Architecture
- NB. Sculpture
- NC. Drawing, Design, Illustration
- ND. Painting
- NE. Print Media
- NK. Decorative Arts
- NX. Arts in General
P. Language and Literature
- P. Philology and Linguistics
- PA. Greek and Latin Languages and Literature
- PB-PH. Modern European Languages
- PJ-PL. Oriental Languages and Literature
- PM. Hyperborean, Indian, and Artificial Languages
- PN. Literature (General)
- PQ. French, Italian, Spanish, and Portuguese Literature
- PR. English Literature
- PS. American Literature
- PT. Germanic Literature
- PZ. Fiction and Juvenile Belles Lettres
Q. Science and Mathematics
- Q. Science (General)
- QA. Mathematics and Computer Science
- 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
- RD. Surgery
- RE. Opthalmology
- RF. Otorhinolaryngology
- RG. Gynecology and Obstetrics
- RJ. Pediatrics
- RK. Dentistry
- DR. Dermatology
- RM. Therapeutics and Pharmacology
- RS. Pharmacy
- RT. Nursing
- RV. Botanic, Thomsonian, and Eclectic Medicine
- RX. Homeopathy
- RZ. Other Systems of Medicine
S. Agriculture
- S. Agriculture (General)
- SB. Plant Culture
- SD. Forestry
- SF. Animal Culture
- SH. Aquaculture, Fisheries, Angling
- SK. Hunting Sports
T. Technology
- T. Technology (General)
- TA. Engineering (General), Civic Engineering
- TC. Hydraulic Engineering, Ocean Engineering
- TD. Environmental Technology, Sanitary Engineering
- TE. Highway Engineering, Roads and Pavements
- TF. Railroad Engineering and Operation
- TG. Bridge Engineering
- TH. Building Construction
- TJ. Mechanical Engineering and Machinery
- TK. Electrical Engineering, Electronics, Nuclear Engineering
- TL. Motor Vehicles, Aeronautics, Astronautics
- TN. Mining Engineering, Metallurgy
- TP. Chemical Technology
- TR. Photography
- TS. Manufactures
- TT. Handicrafts, Arts and Crafts
- TX. Home Economics
U. Military Science
- U. Military Science (General)
- UA. Armies: Organization, Distribution, Military Situation
- UB. Military Administration
- UC. Maintenance and Transportation
- UD. Infantry
- UE. Calvary and Armor
- UF. Artillery
- UG. Military Engineering and Air Forces
- UH. Other Services
V. Naval Science
- V. Naval Science (General)
- VA. Navies: Organization, Distribution, Naval Situation
- VB. Naval Administration
- VC. Naval Maintenance
- VD. Naval Seamen
- VE. Marines
- VF. Naval Ordnance
- VG. Minor Services of Navies
- VK. Navigation and Merchant Marine
- VM. Naval Architecture, Shipbuilding, Marine Engineering
Z. Bibliography, Library Science, and Information Resources
- Z. Books (General), Writing, Books Industries and Trade, Libraries, Bibliography
- ZA. Information Resources (General)
