Gaya APA

Cunningham, W, P., Cunningham, M, A. (2012). Environmental Science A Global Concern twelfth edition (Twelfth edition). USA: The MC Graw Hill Companies.

Gaya MLA

Cunningham, William, P.., Cunningham, Mary, Ann. "Environmental Science A Global Concern twelfth edition". Twelfth edition USA: The MC Graw Hill Companies, 2012. Text.