Modern science problems : a textbook in general science / Ellsworth S. Obourn and Elwood D. Heiss. Science problems. Obourn, Ellsworth Scott 1897- Heiss, Elwood D. (Elwood David) 1899- joint author. Science. 500 OBM Includes bibliographies. St. Louis : Webster Pub., c1936. c1936. 1936 Text v, 322 p. : eng