Certo, S. C., & Certo, S. T. (2009). Modern management: Concepts and skills (11th ed.). Prentice Hall.

Certo, Samuel C., and S. Trevis Certo. Modern Management: Concepts and Skills. 11th ed. Upper Saddle River, NJ ; New Delhi: Prentice Hall, 2009.

Certo, Samuel C., and S. Trevis Certo. Modern Management: Concepts and Skills. 11th ed. Prentice Hall, 2009.