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Dyfyniad Arddull ChicagoWeitz, Barton A. Selling: Building Partnerships. Boston: McGraw-Hill/Irwin, 2007.
Dyfyniad MLAWeitz, Barton A. Selling: Building Partnerships. Boston: McGraw-Hill/Irwin, 2007.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.