Topogràfic
B - Filosofia, Psicologia, Religió
102
H - Social Science
51
L - Education
25
Q - Science
12
S - Agriculture
9
P - Language and Literature
6
G - Geography, Anthropology, Recreation
5
T - Technology
4
N - Fine Arts
3
F - General American History
2
R - Medicine
2
Z - Library Science
2
A - Treballs generalss
1
J - Political Science
1