De Kruif, P., & De Kruif, R. B. (1936). Why keep them alive? Harcourt, Brace and Company.
Dyfyniad Arddull ChicagoDe Kruif, Paul, and Rhea Barbarin De Kruif. Why Keep Them Alive? New York: Harcourt, Brace and Company, 1936.
Dyfyniad MLADe Kruif, Paul, and Rhea Barbarin De Kruif. Why Keep Them Alive? Harcourt, Brace and Company, 1936.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.