Dyfyniad APA

Petersen, J. F., Sack, D. I., & Gabler, R. E. (2011). Fundamentals of physical geography. Brooks/Cole.

Dyfyniad Arddull Chicago

Petersen, James F., Dorothy Irene Sack, and Robert E. Gabler. Fundamentals of Physical Geography. Belmont, CA: Brooks/Cole, 2011.

Dyfyniad MLA

Petersen, James F., et al. Fundamentals of Physical Geography. Brooks/Cole, 2011.

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