Tull, D. S. (1990). Marketing Research Measurement & Method Donald S. Tull And Del I. Hawkins. Macmillan.
Lua i Stíl Chicago (17ú heag.)Tull, Donald S. Marketing Research Measurement & Method Donald S. Tull And Del I. Hawkins. Macmillan, 1990.
Lua MLA (8ú heag.)Tull, Donald S. Marketing Research Measurement & Method Donald S. Tull And Del I. Hawkins. Macmillan, 1990.
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