1. Andersson A and Nilsson K O 1974 Ambio Stockholm 3, 198–200.
2. Andersson A and Nilsson K O 1976 Swedish J. Agric. Res. 6, 151–159.
3. Cataldo D A and Wildung R E 1978 Environ. Health Perspec. 27, 149–159.
4. Cavallaro N and McBride M B 1978 Soil Sci. Soc. Am. J. 42, 550–556.
5. Chaney R Let al. 1975In Proc. of National Conference on Municipal Sludge Management and Disposal. Ed. R C Loehr, Rockville Information Transfer, pp 169–178.