1. Water purification Author(s): Pennsylvania Sanitation Company, author. Publication: [Philadelphia?] : [publisher not identified], [1897?] Subject(s): Water Purification -- methods
2. Filtration Author(s): Maignen, P. A. Publication: Philadelphia : Maignen's Filtration Company, [1898?] Subject(s): Water Purification -- methodsWater SupplyPhiladelphia
3. The filtration of public water supplies Author(s): Leffmann, Henry, 1847-1930 author Publication: [Philadelphia?] : [publisher not identified], [1895?] Subject(s): Water SupplyWater Purification -- methods