Kotler, P., & Armstrong, G. (1999). Principles of marketing (8th ed.). Prentice Hall.

Kotler, Philip, and Gary Armstrong. Principles of Marketing. 8th ed. Upper Saddle River, NJ ; New Delhi: Prentice Hall, 1999.

Kotler, Philip, and Gary Armstrong. Principles of Marketing. 8th ed. Prentice Hall, 1999.