71. Activated sludge studies, 1920-1922 Author(s): Illinois State Water Survey, author, issuing body. Publication: Urbana, Illinois : State of Illinois, Department of Registration and Education, Division of the State Water Survey, [1923] Subject(s): SewageWater PurificationIllinois
72. A sanitary survey of the city of Eugene, Oregon Author(s): Spangler, Paul, 1899-1994, author Publication: Produced: [1923] Subject(s): SanitationHealth SurveysWater SupplyWaste ManagementSewageVital StatisticsOregon
