AC = AC - Collections and Collected Works
AE = AE - Encyclopedias
AG = AG - Dictionaries and Reference
AI = AI - Indexes
AM = AM - Museums and Collecting
AN = AN - Newspapers
AP = AP - Periodicals
AS = AS - Academies
AY = AY - Yearbooks, Almanacs, Directories
AZ = AZ - History of Scholarship
B = B - Philosophy
BC = BC - Logic
BD = BD - Speculative Philosophy
BF = BF - Psychology
BH = BH - Aesthetics
BJ = BJ - Ethics
BL = BL - Religions, Mythology, Rationalism
BM = BM - Judaism
BP = BP - Islam, Bahaism, Theosophy
BQ = BQ - Buddhism
BR = BR - Christianity
BS = BS - The Bible
BT = BT - Doctrinal Theology
BV = BV - Practical Theology
BX = BX - Christian Denominations
C = C - General History
CB = CB - History of Civilization
CC = CC - Archaeology
CD = CD - Diplomatics, Archives, Seals
CE = CE - Technical Chronology, Calendar
CJ = CJ - Numismatics
CN = CN - Inscriptions, Epigraphy
CR = CR - Heraldry
CS = CS - Genealogy
CT = CT - Biography
D = D - General History
DA = DA - Great Britain
DAW = DAW - Central Europe
DB = DB - Austria, Liechtenstein, Hungary, Czechoslovakia
DC = DC - France, Andorra, Monaco
DD = DD - Germany
DE = DE - Grecco-Roman World
DF = DF - Greece
DG = DG - Italy, Malta
DH = DH - Low Countries
DJ = DJ - Netherlands (Holland)
DJK = DJK - Eastern Europe (General)
DK = DK - Russia, Soviet Union, Former Soviet Republics, Poland
DL = DL - Northern Europe, Scandinavia
DP = DP - Spain, Portugal
DQ = DQ - Switzerland
DR = DR - Balkan Peninsula
DS = DS - Asia
DT = DT - Africa
DU = DU - Oceania (South Seas)
DX = DX - Gypsies
E = E - United States History
F = F - General American History
G = G - General Geography
GA = GA - Mathematical Geography and Cartography
GB = GB - Physical Geography
GC = GC - Oceanography
GE = GE - Environmental Sciences
GF = GF - Human Ecology and Anthropogeography
GN = GN - Anthropology
GR = GR - Folklore
GT = GT - Manners and Customs
GV = GV - Leisure and Recreation
H = H - Social Science
HA = HA - Statistics
HB = HB - Economic Theory and Demography
HC = HC - Economic History and Conditions
HD = HD - Industries, Land Use, Labor
HE = HE - Transportation and Communications
HF = HF - Commerce
HG = HG - Finance
HJ = HJ - Public Finance
HM = HM - Sociology
HN = HN - Social History and Conditions
HQ = HQ - Family, Marriage, Women
HS = HS - Societies
HT = HT - Communities, Classes, Races
HV = HV - Social Pathology, Criminology
HX = HX - Socialism, Communism, Anarchism
J = J - General Legislature
JA = JA - Political Science
JC = JC - Political Theory
JF = JF - Public Administration
JJ = JJ - North America
JK = JK - United States
JL = JL - Canada and Central America
JQ = JQ - Europe
JS = JS - Local and Municipal Government
JV = JV - Colonization, Immigration
JX = JX - International Law
JZ = JZ - International Relations
K = K - General Law
KB = KB - Religious Law
KBM = KBM - Jewish Law
KBP = KBP - Islamic Law
KBR = KBR - History of Canon Law
KBU = KBU - Catholic Law
KD = KD - United Kingdom and Ireland
KDZ = KDZ - North America
KE = KE - Canada
KF = KF - United States
KG = KG - Mexico and Central America
KH = KH - South America
KJ = KJ - Europe
KL = KL - Asia, Africa, Pacific
KZ = KZ - Law of Nations
L = L - General Education
LA = LA - History of Education
LB = LB - Theory and Practice of Education
LC = LC - Social Aspects of Education
LD = LD - United States
LE = LE - Canada and Central America
LF = LF - Europe
LG = LG - Asia, Africa, Australia, Pacific
LH = LH - School Magazine and Papers
LJ = LJ - Student Fraternities and Societies
LT = LT - Textbooks
M = M - Music
ML = ML - Literature on Music
MT = MT - Instruction and Study
N = N - Visual Arts
NA = NA - Architecture
NB = NB - Sculpture
NC = NC - Drawing, Design, Illustration
ND = ND - Painting
NE = NE - Print Media
NK = NK - Decorative Arts
NX = NX - Arts in General
P = P - Philology and Linguistics
PA = PA - Latin and Greek
PB = PB - Modern and Celtic Languages
PC = PC - Romanic Languages
PD = PD - Germanic Languages
PE = PE - English Languages
PF = PF - West Germanic Languages
PG = PG - Slavic, Baltic, Abanian Languages
PH = PH - Uralic, Basque Languages
PJ = PJ - Oriental
PK = PK - Indo-Iranian
PL = PL - Eastern Asia, Africa, Oceania
PM = PM - Hyperborean, Indian, and Artificial Languages
PN = PN - General Literature
PQ = PQ - French, Italian, Spanish, Portuguese Literature
PR = PR - English Literature
PS = PS - American Literature
PT = PT - European, Asian and African Literature
PZ = PZ - Fiction
Q = Q - General Science
QA = QA - Mathematics
QB = QB - Astronomy
QC = QC - Physics
QD = QD - Chemistry
QE = QE - Geology
QH = QH - Natural History and Biology
QK = QK - Botany
QL = QL - Zoology
QM = QM - Human Anatomy
QP = QP - Physiology
QR = QR - Microbiology
R = R - General Medicine
RA = RA - Public Medicine
RB = RB - Pathology
RC = RC - Internal Medicine
RD = RD - Surgery
RE = RE - Ophthalmology
RF = RF - Otorhinolarynhology
RG = RG - Gynecology and Obstetrics
RJ = RJ - Pediatrics
RK = RK - Dentistry
RL = RL - Dermatology
RM = RM - Therapeutics and Pharmacology
RS = RS - Pharmacy
RT = RT - Nursing
RV = RV - Botanic, Thomsonia, Eclectic Medicine
RX = RX - Homeopathy
RZ = RZ - Other Systems of Medicine
S = S - General Agriculture
SB = SB - Plant Culture
SD = SD - Forestry
SF = SF - Animal Culture
SH = SH - Aquaculture, Fisheries, Angling
SK = SK - Hunting Sports
T = T - General Technology
TA = TA - General and Civil Engineering
TC = TC - Hydraulic and Ocean Engineering
TD = TD - Environmental Technology
TE = TE - Highway Engineering
TF = TF - Railroad Engineering and Operation
TG = TG - Bridge Engineering
TH = TH - Building Construction
TJ = TJ - Mechanical Engineering and Machinery
TK = TK - Electrical and Nuclear Engineering
TL = TL - Motor Vehicles and Aeronautics
TN = TN - Mining Engineering and Metallurgy
TP = TP - Chemical Technology
TR = TR - Photography
TS = TS - Manufactures
TT = TT - Arts and Crafts
TX = TX - Home Economics
U = U - General Military Science
UA = UA - Armies
UB = UB - Military Administration
UC = UC - Maintenance and Transportation
UD = UD - Infantry
UE = UE - Cavalry and Armor
UF = UF - Artillery
UG = UG - Military Engineering and Air Forces
UH = UH - Other Services
V = V - General Naval Science
VA = VA - Navies
VB = VB - Naval Administration
VC = VC - Naval Maintenance
VD = VD - Naval Seamen
VE = VE - Marines
VF = VF - Naval Ordnance
VG = VG - Minor Services
VK = VK - Navigation and Merchant Marine
VM = VM - Naval Architecture, Shipbuilding, Marine Engineering
Z = Z - Books and Writing
ZA = ZA - Information Resources