Topogràfic
P - Language and Literature
65
Q - Science
50
H - Social Science
49
R - Medicine
21
L - Education
18
D - World History
17
T - Technology
16
N - Fine Arts
10
B - Filosofia, Psicologia, Religió
8
G - Geography, Anthropology, Recreation
7
J - Political Science
4
K - Law
4
Z - Library Science
3
A - Treballs generalss
2
E - United States History
2
S - Agriculture
2
C - Historical Sciences
1
M - Music
1