Classification
EFE - Petroleum geology
4
GHA - Petrology - general
3
EFA - Petroleum, natural gas
1
EFK - Petroleum deposits, natural gas deposits
1
GBAK - Paleontology
1
GCAA - Regional geology - Germany
1
GMK - Geochemistry of elements, minerals, rocks
1
GMP - Geochemical exploration
1
GWB - Raw materials - metals, nonmetals
1