Classification
UPN - Water protection, water quality, clean water
181
UPK - Water resources, water supply
20
UPT - Water pollution control and measurement
20
UPP - Water pollution
15
UPVF - Surface waters - streams, rivers, lakes
11
LCO - Hydrobiology
10
UPCE - Water chemistry
10
UPW - Drinking water
9
UPVC - Groundwater
8
URA - Soil chemistry
8
GTA - Hydrology - general
7
USN - Waste water treatment
7
UPC - Water - general aspects
6
LHH - Microbiology - methods
5
TAT - Engineering Standards
5
YEC - Law on waters
5
UPA - Water - handbooks
4
LCK - Ecology - general aspects
3
LCR - Ecology of microorganisms - land and water
3
LWE - Agriculture - general aspects
3
UMG - Technology of clean air
3
USNG - Waste water treatment - biological aspects
3
GTAK - Hydrogeology
2
LCL - Biotopes, ecosystems
2
UCE - Environmental impact, environmental pollution
2
UCJ - Environmental protection - general aspects
2
UHN - Landscape ecology
2
UMN - Air pollution control and measurement
2
USR - Slurry, sludge - treatment and use
2
UVC - Environmental chemicals, hazardous materials - general aspects
2
CHRV - Water and its properties
1
CMDS - Photochemical processes in nature and technology
1
CWE - Chemical engineering, chemical industry - general
1
CWOL - Filtration
1
EHA - Renewable energy sources
1
EMA - Hydroelectric, tidal energy
1
FGN - Nanotechnology
1
FNPE - Nanostructured materials
1
GAN - Geosciences - mathematical methods, computer applications
1
GCAA - Regional geology - Germany
1
GHAB - Rocks - physical properties
1
GMAB - Hydrogeochemistry
1
GMAD - Organic geochemistry
1
GPAB - Flora, vegetation - geographical aspects
1
GRA - Meteorology
1
GRBA - Climatology - general
1
GTAP - Hydrological investigation methods
1
GUAA - Geography - physical
1
GVA - Oceanography
1
LCNC - Soil science - water transport
1
more ...