Dyfyniad APA

Enger, E. D., & Smith, B. F. (2004). Environmental science: A study of interrelationships (9th ed.). Mc Graw hill.

Dyfyniad Arddull Chicago

Enger, Eldon D., and Bradley Fraser Smith. Environmental Science: A Study of Interrelationships. 9th ed. Boston: Mc Graw hill, 2004.

Dyfyniad MLA

Enger, Eldon D., and Bradley Fraser Smith. Environmental Science: A Study of Interrelationships. 9th ed. Mc Graw hill, 2004.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.