Gaya APA

Oster, K, E, C, R, C, F, S, M. (2013). Principles of economics: pearson horizon editions (ed. 10). Boston: Pearson.

Gaya MLA

Oster, Karl, E., Case;, Ray, C., Fair;, Sharon, M.. "Principles of economics: pearson horizon editions". ed. 10 Boston: Pearson, 2013. Text.