APA (7th ed.) Citation

Irwin, Walton, G., & Wykoff, F. (1991). Understanding economics today (3th ed.). Irwin.

Chicago Style (17th ed.) Citation

Irwin, Gary Walton, and Frank Wykoff. Understanding Economics Today. 3th ed. Boston: Irwin, 1991.

MLA (8th ed.) Citation

Irwin, et al. Understanding Economics Today. 3th ed. Irwin, 1991.