Bryce Ryan, Neal C. Gross: The diffusion of hybrid seed corn in two Iowa communities. In: Rural Sociology. Bd. 8, Nr. 1, 1943, ISSN0036-0112, S. 15–24, (Digitalisat).
reader.library.cornell.edu
Edward Hassinger: Stages in the adoption process. In: Rural Sociology. Bd. 24, Nr. 1, 1959, S. 52–53, (Digitalisat).
zdb-katalog.de
Bryce Ryan, Neal C. Gross: The diffusion of hybrid seed corn in two Iowa communities. In: Rural Sociology. Bd. 8, Nr. 1, 1943, ISSN0036-0112, S. 15–24, (Digitalisat).