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Dyfyniad Arddull ChicagoAudesirk, Teresa, Gerald Audesirk, and Bruce E. Byers. Life on Earth. 2nd ed. Upper Saddle River, N.J: Prentice Hall, 2000.
Dyfyniad MLAAudesirk, Teresa, et al. Life on Earth. 2nd ed. Prentice Hall, 2000.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.