GRIKSCHEIT GRAY M. (1981). HANDBOOK OF SELLING. JOHN WILEY AND SONS.
Lua i Stíl Chicago (17ú heag.)GRIKSCHEIT GRAY M. HANDBOOK OF SELLING. NEW DELHI: JOHN WILEY AND SONS, 1981.
Lua MLA (9ú heag.)GRIKSCHEIT GRAY M. HANDBOOK OF SELLING. JOHN WILEY AND SONS, 1981.
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