1. Python Knowledge Engine (Pyke). http://pyke.sourceforge.net/. [Online; retrieved July 2015]. Python Knowledge Engine (Pyke). http://pyke.sourceforge.net/. [Online; retrieved July 2015].
2. L. Andersson and E. Rosen. Framework for Layer 2 Virtual Private Networks (L2VPNs). RFC 4664 Jul 2008. L. Andersson and E. Rosen. Framework for Layer 2 Virtual Private Networks (L2VPNs). RFC 4664 Jul 2008.
3. D. Fedyk Y. Rekhter D. Papadimitriou R. Rabbat and L. Berger. Layer 1 VPN Basic Mode. RFC 5251 Jul 2008. D. Fedyk Y. Rekhter D. Papadimitriou R. Rabbat and L. Berger. Layer 1 VPN Basic Mode. RFC 5251 Jul 2008.