Williams A.
Methane Emissions. London: Watt Committee on Energy; 1994.
WHO.
Environmental Health Criteria 61 Chromium. Geneva: World Health Organisation; 1988.
WHO.
Air Quality Guidelines for Europe. . Copenhagen: World Health Organisation; 2000.
WHO.
Effects of atmospheric nitrogen compounds (particularly nitrogen oxides) on plants. In: Environmental Health Criteria Series. Vol. 188. Environmental Health Criteria Series. Geneva: WHO; 1997. pp. 115–191.