Land disposal : hazardous waste : proceedings of the seventh annual research symposium at Philadelphia, Pennsylvania, March 16-18, 1981, sponsored by the U.S. EPA, Office of Research & Development, Municipal Environmental Research Laboratory, Solid and Hazardous Waste Research Division / - Shultz, David W.; Black, David, (Municipal Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency ;, 1981)