Topogràfic
L - Education
710
H - Social Science
40
R - Medicine
39
P - Language and Literature
29
K - Law
27
N - Fine Arts
15
F - General American History
14
J - Political Science
11
B - Filosofia, Psicologia, Religió
7
D - World History
7
Q - Science
7
T - Technology
5
G - Geography, Anthropology, Recreation
3
S - Agriculture
3
C - Historical Sciences
2
Z - Library Science
2
A - Treballs generalss
1
M - Music
1