Gaya APA

Kreps, C, F, &, J, M. (1962). Principles of Economics (--). United Stetes Of America: Holt, Rinehart and Winston, Inc.

Gaya MLA

Kreps, C.E., Ferguson, &, Juanita, M. "Principles of Economics". -- United Stetes Of America: Holt, Rinehart and Winston, Inc, 1962. Text.