Classification
GWA - Raw material economy, raw material policy
156
GCAC - Regional geology - noneuropean countries
9
GWBA - Raw material resources, raw material reserves
7
EXA - Energy policy
5
AZZ - Firm index - general
4
GWB - Raw materials - metals, nonmetals
4
ECA - Energy resources
3
EFA - Petroleum, natural gas
3
GDA - Engineering geology - general
3
GMP - Geochemical exploration
3
UED - Environmental policy
3
CEO - Natural organic products
2
GCAB - Regional geology - european countries
2
GWC - Ore deposits
2
UEF - Sustainability
2
UEN - Environmental economy
2
YPB - Economy - general aspects
2
YPO - Economic policy
2
YPW - Economy of industry branches
2
CWE - Chemical engineering, chemical industry - general
1
CXA - Coal and fossil fuel - chemistry and technology
1
CXRS - Petroleum
1
EFP - Petroleum production, natural gas production
1
EHA - Renewable energy sources
1
ENA - Energy from biomass and waste
1
EWA - Energy economy
1
FMP - Ferrous materials, steel
1
GBAA - Geology - textbooks
1
GCA - Regional geology
1
GCAA - Regional geology - Germany
1
GFA - Mineralogy - general
1
GHMA - Clay, shale
1
GRBN - Climatological models
1
GTA - Hydrology - general
1
GUA - Geography - general
1
GWAA - Raw material programs
1
GWAB - National raw material reports
1
GWD - Marine mineral resources
1
GXAB - Polar research - antarctic region
1
LWO - Agricultural ecology, sustainable agriculture
1
UCA - Environmental problems, man and environment - general aspects
1
UEA - Environmental policy and economy - general aspects
1
UMD - Atmospheric models
1
UMV - Climatic change
1
UPK - Water resources, water supply
1
YDA - Administrative law
1
YZA - Politics, political science
1