Clark, Ella E.2019-01-072019-01-071957-03EPM-069-09-001http://hdl.handle.net/20.500.11867/151459 sheets 6.5 x 9.5 inch. Printed recto and verso. Front sheet inscribed.Reprinted from "Research Studies of the State College of Washington," XXV:1. Includes extensive footnotes, throughout.