1. Hudson , H. E. , Jr. How Serious Is the Problem? Proc. 10th San. Engr. Conf. of Illinois Urbana, Ill. 1968
2. Doe , P. W. A Report on the Disposal of Sludge from Water Treatment Plants British Water Works Assoc. Jubilee Traveling Scholarship 1966-67
3. Tokyo's Aska Purification Plant;Fujita;Water and Sewage Works,1967
4. Recovery and Reuse of Alum Sludge at Tampa;Roberts;Jour. AWWA,1960