Topogràfic
H - Social Science
125
P - Language and Literature
49
R - Medicine
30
L - Education
17
K - Law
11
B - Filosofia, Psicologia, Religió
9
A - Treballs generalss
5
Q - Science
5
F - General American History
4
N - Fine Arts
4
D - World History
3
G - Geography, Anthropology, Recreation
2
J - Political Science
2
T - Technology
2
U - Military Science
2
C - Historical Sciences
1
E - United States History
1
M - Music
1