APA (7th ed.) Citation

Kotler, P., & Armstrong, G. (1989). Principles of marketing (4th ed.). Printing Co.

Chicago Style (17th ed.) Citation

Kotler, Philip, and Gary Armstrong. Principles of Marketing. 4th ed. Metro Manila: Printing Co, 1989.

MLA (9th ed.) Citation

Kotler, Philip, and Gary Armstrong. Principles of Marketing. 4th ed. Printing Co, 1989.