Keeton, W. T. (1972). Elements of biological science (2nd ed.). W.W. Norton.
Dyfyniad Arddull ChicagoKeeton, William T. Elements of Biological Science. 2nd ed. New York: W.W. Norton, 1972.
Dyfyniad MLAKeeton, William T. Elements of Biological Science. 2nd ed. W.W. Norton, 1972.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.