Dyfyniad APA

Keller, E. A. (2012). Introduction to environmental geology (Fifth edition.). Prentice Hall.

Dyfyniad Arddull Chicago

Keller, Edward A. Introduction to Environmental Geology. Fifth edition. Upper Saddle River, New Jersey: Prentice Hall, 2012.

Dyfyniad MLA

Keller, Edward A. Introduction to Environmental Geology. Fifth edition. Prentice Hall, 2012.

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