Update README.md

Author: mayankrs

README.md

@@ -10,4 +10,5 @@ NAT64 allows IPv6-only clients to connect to IPv4 servers using unicast TCP, UDP
 
 ### References
 [1] [Stateful NAT64 - RFC 6146](https://tools.ietf.org/html/rfc6146)  
-[2] [Google Summer of Code (GSoC) ns-3 project on NAT](https://www.nsnam.org/wiki/GSOC2012NetworkAddressTranslation)
+[2] [Google Summer of Code (GSoC) ns-3 project on NAT](https://www.nsnam.org/wiki/GSOC2012NetworkAddressTranslation)  
+[3] [NAT64 Technology - CISCO](https://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/enterprise-ipv6-solution/white_paper_c11-676278.html)