APA (7th ed.) Zitazioa
Gregory, P. R. (1990). Essentials of economics (2nd ed.). Scott, Foresman.
Chicago Style (17th ed.) Zitazioa
Gregory, Paul R. Essentials of Economics. 2nd ed. Glenview, Ill.: Scott, Foresman, 1990.
MLA (9th ed.) Zitazioa
Gregory, Paul R. Essentials of Economics. 2nd ed. Scott, Foresman, 1990.
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