Clark, J. (1985). Study Guide to Accompany Gwartney, Stroup, and Clark's Essentials of Economics (Second Edition). ELSEVIER.
Lua i Stíl Chicago (17ú heag.)Clark, J.R. Study Guide to Accompany Gwartney, Stroup, and Clark's Essentials of Economics (Second Edition). ELSEVIER, 1985.
Lua MLA (8ú heag.)Clark, J.R. Study Guide to Accompany Gwartney, Stroup, and Clark's Essentials of Economics (Second Edition). ELSEVIER, 1985.
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