Boettcher, R. A., Air classification of solid wastes : performance of experimental units and potential applications for solid waste reclamation / by R. A. Boettcher - Washington,D.C. : United States Environmental Protection Agency, 1972 - viii, 73 p. : ill. ; 26 cm. Subjects--Topical Terms: Solid wastes--Disposal TechnologySalvage (Waste, etc.)Separation (Technology) Dewey Class. No.: 628.445