1. Septic systems handbook;Kaplan,1991
2. Metcalf, Eddy. Wastewater engineering: treatment, disposal, and re-use. New York: McGraw-Hill, 1991.
3. Septic tanks—problems and practice;Butler;Building Environ,1995
4. Problems associated with the use of gravel in septic-tank leachfield systems;May;J Environ Health,1996
5. Small and decentralized wastewater management systems;Crites,1998