Klassifikationsnummer
D - World History
10
T - Technology
7
F - General American History
5
P - Language and Literature
5
A - General Works
3
G - Geography, Anthropology, Recreation
2
H - Social Science
2
J - Political Science
2
K - Law
2
B - Philosophy, Psychology, Religion
1
C - Historical Sciences
1
L - Education
1
Q - Science
1