APA (7th ed.) Citation

Dang, L., Jennings, C., & Kelly, D. (2002). Practical VoIP using Vocal. O'Reilly.

Chicago Style (17th ed.) Citation

Dang, Luan, Cullen Jennings, and David Kelly. Practical VoIP Using Vocal. Sebastopol, CA: O'Reilly, 2002.

MLA (9th ed.) Citation

Dang, Luan, et al. Practical VoIP Using Vocal. O'Reilly, 2002.