A	General Works
B	Philosophy. Psychology. Religion
C	Auxiliary Sciences of History
D	History (General) and History of Europe
E	History : America
F	History : America
G	Geography. Maps. Anthropology. Recreation
H	Social Sciences
	H - HJ -- Economics
	HM - HX -- Sociology
J	Political Science
K	Law
L	Education
M	Music and Books on Music
N	Fine Arts
	NA -- Architecture
P	Language and Literature
	PE -- English
Q	Science (General)
	QA -- Mathematics. Computer science. Electronic data processing
	QB -- Astronomy
	QC -- Physics
	QD -- Chemistry
	QE -- Geology
R	Medicine
S	Agriculture
T	Technology (General)
	TA -- Engineering (General). Civil engineering (General)
	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
V	Naval Science
Z	Bibliography. Library Science. Information Resources.