1. Black, S.A. and Schmidtke, N.W. 1979. “Practises and Trends in Sewage Sludge Utilization and Disposal”. presented at 1st Workshop on Canadian‐German Cooperation. 1979, Burlington, Ontario.
2. Bunch, R.L. 1981. “Sewage Sludge Diletanaof the Eighties”. presented at 3rd International Conference on Physicochemical Methods for Water and Wastewater Treatment. 1981, Lubin, Poland.