Gaya APA

Cunningham, W, P., Cunningham, M, A. (2013). Principles of Environmental Science: inquiry & applications seventh edition (seventh edition). New York: McGraw-Hill Irwin.

Gaya MLA

Cunningham, William, P.., Cunningham, Mary, Ann. "Principles of Environmental Science: inquiry & applications seventh edition". seventh edition New York: McGraw-Hill Irwin, 2013. ML.