Leedy, P. D. (1985). Practical research: Planning and design (3rd ed.). Macmillan.
Dyfyniad Arddull ChicagoLeedy, Paul D. Practical Research: Planning and Design. 3rd ed. New York: Macmillan, 1985.
Dyfyniad MLALeedy, Paul D. Practical Research: Planning and Design. 3rd ed. Macmillan, 1985.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.