Forbush, D. R. (1987). Study guide and problems to accompany economics (8ª ed.). Harper and Row.
Lua i Stíl Chicago (17ú heag.)Forbush, Dascomb R. Study Guide and Problems to Accompany Economics. 8ª ed. Harper and Row, 1987.
Lua MLA (9ú heag.)Forbush, Dascomb R. Study Guide and Problems to Accompany Economics. 8ª ed. Harper and Row, 1987.
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