Botkin, D. B., & Keller, E. A. (1982). Environmental studies. C.E. Merrill Pub. Co..
Chicago Edition CitationBotkin, Daniel B., i Edward A. Keller. Environmental Studies. Columbus, [Ohio]: C.E. Merrill Pub. Co., 1982.
Cita MLABotkin, Daniel B., i Edward A. Keller. Environmental Studies. C.E. Merrill Pub. Co., 1982.
Atenció: Aquestes cites poden no estar 100% correctes.