Topogràfic
L - Education
21
H - Social Science
16
Q - Science
11
R - Medicine
10
B - Filosofia, Psicologia, Religió
8
K - Law
5
T - Technology
5
P - Language and Literature
4
G - Geography, Anthropology, Recreation
2
S - Agriculture
2
Z - Library Science
2
A - Treballs generalss
1
F - General American History
1
J - Political Science
1
N - Fine Arts
1