Page 79 in Extension Circular 532, Review of Extension Research, January through December 1959, U.S. Department of Agriculture, Washington, D.C. Summary of research report, College of Agriculture, University of Illinois, Urbana. 1959. 24 pages.
Pages 79-80 in Extension Circular 532, Review of Extension Research, January through December 1959, U.S. Department of Agriculture, Washington, D.C. Summary of research report, master of science in agricultural education, University of Minneapolis, St. Paul. 1959
