Classification
AHZ - History of science and technology
2
EXA - Energy policy
1
FAHH - Materials research - historical aspects
1
FAQ - Materials research - institutions, research and development
1
FGM - Microelectronic technology
1
PAD - Physics - comprehensive works
1
PAE - Physics - general interest
1
PKK - Theory of fields and particles - general
1
UXPN - Nonproliferation, nuclear weapons
1