Topogràfic
F - General American History
65
P - Language and Literature
59
D - World History
31
H - Social Science
26
J - Political Science
17
B - Filosofia, Psicologia, Religió
11
L - Education
6
K - Law
5
R - Medicine
5
N - Fine Arts
4
Q - Science
4
G - Geography, Anthropology, Recreation
3
M - Music
3
C - Historical Sciences
2
T - Technology
2
V - Naval Science
1
Z - Library Science
1