Classification
UCN - Environmental education
60
UCA - Environmental problems, man and environment - general aspects
10
UED - Environmental policy
8
UCL - Environmental research
6
UCJ - Environmental protection - general aspects
5
UVC - Environmental chemicals, hazardous materials - general aspects
2
YPO - Economic policy
2
AHF - Research and science
1
HDG - Psychology, psychiatry
1
HYE - Environmental health
1
UAX - Environment - information systems, literature guides
1
UCE - Environmental impact, environmental pollution
1
UCQ - Environmental technology
1
UEA - Environmental policy and economy - general aspects
1
UEN - Environmental economy
1
UHK - Traffic and environment - incl. automobile exhaust gas
1
UMLN - Air pollution by other sources
1
USGT - Waste prevention
1
YRA - Social studies
1
YRB - Social sciences, sociology
1