1. Xiaotao Wu, Henning Schulzrinne, LESS: language for end system services in Internet telephony. Internet Draft draft-wu-iptel-less, IETF, February 2005. Work in progress.
2. Xiaotao Wu, Henning Schulzrinne, Programmable end system services using SIP, in: Proceedings of Conference Record of the International Conference on Communications (ICC), May 2003, pp. 789–793.
3. Jonathan Lennox, Xiaotao Wu, Henning Schulzrinne, Call processing language (CPL): a language for user control of Internet telephony services. RFC 3880, Internet Engineering Task Force, October 2004.
4. Xiaotao Wu, Henning Schulzrinne, End system service examples. Technical Report CUCS-048-04, Columbia University Department of Computer Science, New York, December 2004.
5. AT&T. 5ESS switch, the premier solution, feature handbook, issue 4, September 1987.