Forbush, D. R. (1987). Study guide and problems to accompany economics (8ª ed.). Harper and Row.
Chicago-viite (17. p.)Forbush, Dascomb R. Study Guide and Problems to Accompany Economics. 8ª ed. Harper and Row, 1987.
MLA-viite (9. p.)Forbush, Dascomb R. Study Guide and Problems to Accompany Economics. 8ª ed. Harper and Row, 1987.
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