[1] Overview of Frame Relay. http://www.dcbnet.com/notes/framerly.htm
[2] Frame Relay Tutorial, http://www.scan-technologies.com/tutorials/frame relay turorial.htm
[3] X.25, www.cisco.com
[4] Introduction to wan technologies, www.cisco.com
[5] WAN-Wide Area Network, www.rad.com/networks/1994/networks/wan.htm
[6] X.25—Packet Transmision Prtotocol by Cheung Harvey Wai-Lun. www.wpi.edu
[8] Wan Technologies Overview, www.lads.com/~pbodor/wanmain.html
[9] The Basic Guide to Frame Relay Networking, www.frforum.com
[10] Frame Relay, www.cisco.com