The following resources may be consulted for further information. Resources are listed here as examples only, and no endorsement of any company or software package is implied.
The formal IEEE standards are a moving target: old versions of the standards are periodically updated, and new standards are often being developed.
Interconnections: Bridges, Routers, Switches and Internetworking Protocols (2nd Edition), by Radia Perlman. Addison-Wesley. 1999.