Topogràfic
Q - Science
465
L - Education
447
H - Social Science
209
R - Medicine
145
S - Agriculture
106
P - Language and Literature
46
T - Technology
41
B - Filosofia, Psicologia, Religió
34
J - Political Science
28
G - Geography, Anthropology, Recreation
25
A - Treballs generalss
19
K - Law
16
N - Fine Arts
11
Z - Library Science
9
C - Historical Sciences
7
D - World History
7
F - General American History
2