1. Simplified Rapid Sand Filter System;Hudson;Wtr. & Sew. Wks.,1959
2. Baylis , J. R. Preliminary Report on Chemical Treatment of Lake Michigan Water at Chicago Unpublished 1931
3. Bryant , E. A. Hudson , H. E. , Jr. Laboratory Tests on Removal of Manganese With Alum Treatment Memo., Hazen & Sawyer, Engrs., New York 1958
4. Hazen , A. Report of the Filtration Commission of the City of Pittsburgh, Pa 1899