APA (7th ed.) Citation

ScienceDirect (Online service), Henmi, A., Lucas, M., Singh, A., & Cantrell, C. (2006). Firewall policies and VPN configurations. Syngress.

Chicago Style (17th ed.) Citation

ScienceDirect (Online service), Anne Henmi, Mark Lucas, Abhishek Singh, and Chris Cantrell. Firewall Policies and VPN Configurations. Rockland, MA: Syngress, 2006.

MLA (9th ed.) Citation

ScienceDirect (Online service), et al. Firewall Policies and VPN Configurations. Syngress, 2006.