COOPER DONALD R. (2008). BUSINESS RESEARCH METHODS [WITH CD] (9TH.). TATA MCGRAW-HILL PUBLISHING COMPANY LIMITED.
Lua i Stíl Chicago (17ú heag.)COOPER DONALD R. BUSINESS RESEARCH METHODS [WITH CD]. 9TH. NEW DELHI: TATA MCGRAW-HILL PUBLISHING COMPANY LIMITED, 2008.
Lua MLA (9ú heag.)COOPER DONALD R. BUSINESS RESEARCH METHODS [WITH CD]. 9TH. TATA MCGRAW-HILL PUBLISHING COMPANY LIMITED, 2008.
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