Classification
YPB - Economy - general aspects
YBB - Law - general
3
YDA - Administrative law
2
YPC - Public administration
2
AAA - Encyclopedias - general aspects
1
AHF - Research and science
1
EWA - Energy economy
1
EXA - Energy policy
1
HDG - Psychology, psychiatry
1
TKJ - Traffic
1
UED - Environmental policy
1
YPG - Business management
1
YRA - Social studies
1
YRB - Social sciences, sociology
1
YZA - Politics, political science
1