索引號
S - Agriculture
614
T - Technology
304
N - Fine Arts
3
C - Historical Sciences
2
A - General Works
1
B - Philosophy, Psychology, Religion
1
E - United States History
1
F - General American History
1
G - Geography, Anthropology, Recreation
1
L - Education
1
M - Music
1
P - Language and Literature
1
R - Medicine
1