Topogràfic
H - Social Science
49
J - Political Science
26
F - General American History
21
P - Language and Literature
14
L - Education
13
Q - Science
10
B - Filosofia, Psicologia, Religió
9
G - Geography, Anthropology, Recreation
7
K - Law
4
C - Historical Sciences
2
T - Technology
2
A - Treballs generalss
1
E - United States History
1
N - Fine Arts
1
R - Medicine
1
Z - Library Science
1