1. Communications with the superintendent of Lima, Ohio, water treatment plant and with representatives of Calgon Corp Detroit, Mich. 1974
2. Study of Chemicals Used for Cleaning Rapid Sand Filters;Geyer;Jour. AWWA,1937
3. Patrick , J.G. Cleaning Filters with Sulfur Dioxide Wtr. & Sewage Works 1938
4. Angle Clyde F. Cleaning Filter Sand with Sulfur Dioxide: A Recent Experience in an Eight-MGD Plant Wtr. & Sewage Works 1947
5. Conventional Lime Soda Ash Softening vs Split Treatment at the Owosso, Mich., Water-Treatment Plant;Singhal;Jour. AWWA,1977