Topogràfic
R - Medicine
135
H - Social Science
120
Q - Science
82
T - Technology
55
L - Education
54
S - Agriculture
27
P - Language and Literature
22
G - Geography, Anthropology, Recreation
15
B - Filosofia, Psicologia, Religió
14
J - Political Science
5
Z - Library Science
4
M - Music
3
C - Historical Sciences
2
N - Fine Arts
2
A - Treballs generalss
1
D - World History
1
K - Law
1
U - Military Science
1