Classification
AHZ - History of science and technology
136
MAH - Mathematics - history
31
CAD - Chemistry - comprehensive works
22
AFG - Large scale research institutions (Helmholtz Centres)
17
AHX - History - general
17
PAE - Physics - general interest
16
AHP - Philosophy
13
ZBAG - Library history
10
YPB - Economy - general aspects
9
CAH - Chemistry - history
8
UCA - Environmental problems, man and environment - general aspects
8
YRC - Technology and society
8
AHF - Research and science
7
AXD - Local studies
7
EPK - Nuclear energy
7
ALD - Biographies of scientists and Nobel prize winners - collected
6
GBA - General geology, historical geology
6
ZAC - Bibliology
6
AET - Universities, academies - Europe
5
MAE - Mathematics - general interest
5
PLA - Astrosciences - general
5
YZA - Politics, political science
5
ZAD - Book trade, publishing
5
AAA - Encyclopedias - general aspects
4
AHM - Theory of science
4
GRB - Climatology
4
HAE - Popular medicine
4
LAM - Biology - theoretical and philosophical fundamentals
4
TKB - Civil engineering - buildings
4
TNA - Nuclear engineering - general
4
ZBJ - Library types
4
ZBJC - German libraries
4
AAE - Popular science - general aspects
3
ABM - Special subject biographies
3
ALE - Biographies of scientists and Nobel prize winners - individual
3
DAE - Information technology - general
3
GBAH - Stratigraphy, history of earth
3
LCK - Ecology - general aspects
3
LWE - Agriculture - general aspects
3
PJA - Atomic physics - general
3
TCL - High frequency engineering
3
THH - Machines
3
UMV - Climatic change
3
YPO - Economic policy
3
YRA - Social studies
3
ZBEBB - Subject indexing
3
ABA - General international and supranational biographic catalogues
2
AFC - Research institutions, scientific organizations - Germany ( DFG, MPG, FHG )
2
AHA - Research and development, research politics - general
2
AHC - Research and development, research politics - Germany
2
more ...