Classification
EFN - Petroleum exploration, natural gas exploration
52
EFE - Petroleum geology
3
EFP - Petroleum production, natural gas production
3
GDA - Engineering geology - general
3
GKK - Geophysics - applications
3
GMAD - Organic geochemistry
3
EFK - Petroleum deposits, natural gas deposits
2
EWA - Energy economy
2
ECA - Energy resources
1
EFA - Petroleum, natural gas
1
EGA - Oil shale, oil sands
1
EVN - Energy supply - future aspects
1
GBAK - Paleontology
1
GHH - Sedimentary petrography - general
1
GMP - Geochemical exploration
1
TND - Gas cooled reactor types
1
UKE - Environment and energy resources
1