RUDDICK M E. (1983). MARKETING RESEARCH HANDBOOK: A DECISION ORIENTED APPROACH. PRENTICE -HALL INTERNATIONAL, INC.
Lua i Stíl Chicago (17ú heag.)RUDDICK M E. MARKETING RESEARCH HANDBOOK: A DECISION ORIENTED APPROACH. NEW JERSEY: PRENTICE -HALL INTERNATIONAL, INC, 1983.
Lua MLA (9ú heag.)RUDDICK M E. MARKETING RESEARCH HANDBOOK: A DECISION ORIENTED APPROACH. PRENTICE -HALL INTERNATIONAL, INC, 1983.
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