(1970). Modern Business: Sales And Sales Management / Elmer G. Leterman. Alexander Hamilton Institute.
Lua i Stíl Chicago (17ú heag.)Modern Business: Sales And Sales Management / Elmer G. Leterman. Alexander Hamilton Institute, 1970.
Lua MLA (8ú heag.)Modern Business: Sales And Sales Management / Elmer G. Leterman. Alexander Hamilton Institute, 1970.
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