Classification
D - World History
22
M - Music
18
H - Social Science
12
Q - Science
11
S - Agriculture
10
T - Technology
7
L - Education
3
P - Language and Literature
3
J - Political Science
2
R - Medicine
2
A - General Works
1
B - Philosophy, Psychology, Religion
1
E - United States History
1
K - Law
1
N - Fine Arts
1