1) U. S. Department of Health, Education, and Welfare: Contaminant removal from sewage plant effluents by foaming (AWTR-5), Public Health Service, Ohio, 1963, pp. 1-56.
2) Georgia Kraft Company: Foam separation of kraft pulping wastes (Water pollution control research series DAST-3), U. S. Federal water pollution control administration, Ohio, 1969, pp. 1-81.