Classification
USN - Waste water treatment
USK - Waste water
5
UPN - Water protection, water quality, clean water
4
UPT - Water pollution control and measurement
4
LHH - Microbiology - methods
1
UAA - Environment - reference books
1
UAD - Environment - comprehensive works
1
UPC - Water - general aspects
1
USNG - Waste water treatment - biological aspects
1
USNH - Waste water treatment - special methods
1
USR - Slurry, sludge - treatment and use
1