ISO 10589, "Intermediate System to Intermediate System"; RFC 1195, "Use of OSI IS-IS for Routing in TCP/IP and Dual Environments," http://www.isi.edu/in-notes/rfc1195.txt
6.
Perlman, Radia. Interconnections, Second Edition: Bridges, Routers, Switches, and Internetworking Protocols (Boston, Mass.: Addison-Wesley Longman, Inc., 1999)
7.
Moy, John. OSPF: Anatomy of an Internet Routing Protocol (Boston, Mass.: Addison-Wesley Longman, Inc., 1998)