Janet L Hopson. (1990). Essentials of biology. New York: McGraw-Hill.
Dyfyniad Arddull ChicagoJanet L Hopson. Essentials of Biology. New York: McGraw-Hill, 1990.
Dyfyniad MLAJanet L Hopson. Essentials of Biology. New York: McGraw-Hill, 1990.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.