1. ITU. Recommendation H.323. Packet-base multimedia communications systems, 1999.
2. et al. SIP: session initiation protocol. RFC 3261, Internet Engineering Task Force, http://www.ietf.org/rfc/rfc3261.txt, 2002.
3. Access Grid. http://www.accessgrid.org, 2003.
4. Global Multimedia Collaboration System (Global-MMCS). http://www.globalmmcs.org