FRIEDRICH, K. (1974). International Economics Concepts And Issues Klaus Friedrich. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)FRIEDRICH, Klaus. International Economics Concepts And Issues Klaus Friedrich. McGraw-Hill, 1974.
Lua MLA (8ú heag.)FRIEDRICH, Klaus. International Economics Concepts And Issues Klaus Friedrich. McGraw-Hill, 1974.
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