Gaya APA

Walton, ., Wykoff, B, M, U. (1991). Study Guide for Use With Understanding Economics Today (Ed.: ke-3). USA: Richard D Irwin, Inc..

Gaya MLA

Walton, ., Wykoff, Brown, Marian, U. "Study Guide for Use With Understanding Economics Today". Ed.: ke-3 USA: Richard D Irwin, Inc., 1991. Text.