Kotler, P., & Gray Armstrong. (1992). Principles of marketing (5th ed.). Prentice-Hall.
Dyfyniad Arddull ChicagoKotler, Philip, and Gray Armstrong. Principles of Marketing. 5th ed. New Delhi: Prentice-Hall, 1992.
Dyfyniad MLAKotler, Philip, and Gray Armstrong. Principles of Marketing. 5th ed. Prentice-Hall, 1992.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.