Ryan, William T.
Programmed learning ald for principles of marketing / William T. Ryan, Roger H. Hermanson
Learning System Company, 1971
 Buku Teks SO
Ryan, William T
Principles of marketing/ by William Ryan
Richard D. Irwin, 1980
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Ryan, William T.
A Guide to marketing / William T. Ryan
Richard D. Irwin, 1981
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Ryan, William
Programed Learning Aid for Principle of Marketing
Learning System of Company, 1971
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Randall, Geoffrey
Principles of marketing
Routledge, 1993
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