Colis, O. L. 1. (1972). Programmed instruction in farmers' cooperative. s. n.
Chicago Style aipamenaColis, Oscar Loyola 1936. Programmed Instruction in Farmers' Cooperative. College, Laguna: s. n, 1972.
MLA aipamenaColis, Oscar Loyola 1936. Programmed Instruction in Farmers' Cooperative. s. n, 1972.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.