Classification
D - World History
23
R - Medicine
16
B - Philosophy, Psychology, Religion
14
F - General American History
9
Q - Science
5
S - Agriculture
4
A - General Works
3
G - Geography, Anthropology, Recreation
3
P - Language and Literature
3
C - Historical Sciences
2
Z - Library Science
2
K - Law
1
N - Fine Arts
1
T - Technology
1