Classification
YED - Law on clean air
20
YEA - Environmental law
9
UMN - Air pollution control and measurement
4
UMEE - Clean air planning
3
UMG - Technology of clean air
2
UMK - Air pollution - general aspects
2
UA - Environment - general
1
UED - Environmental policy
1
UEDM - Policy of clean air
1
UMGN - Flue gas desulfurization
1
UML - Air pollution by special sources
1
UMNE - Air pollution by gaseous pollutants
1
UNA - Noise pollution
1