CRASK, M. (1994). Marketing Research Principles & Applications Melvin Crask, Richard J. Fox, Roy G. Stout. Prentice - Hall.
Lua i Stíl Chicago (17ú heag.)CRASK, Melvin. Marketing Research Principles & Applications Melvin Crask, Richard J. Fox, Roy G. Stout. Prentice - Hall, 1994.
Lua MLA (8ú heag.)CRASK, Melvin. Marketing Research Principles & Applications Melvin Crask, Richard J. Fox, Roy G. Stout. Prentice - Hall, 1994.
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