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Dyfyniad Arddull ChicagoRies, Al, and Jack Trout. Bottom-up Marketing. New York: McGraw-Hill, 1989.
Dyfyniad MLARies, Al, and Jack Trout. Bottom-up Marketing. McGraw-Hill, 1989.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.