1. Clark, J. (2001), “RELAX NG specification”. Available at: www.oasis‐open.org/committees/relax‐ng/spec‐20010811.html
2. Costello, R. (2001), “Extending XML schemas”. Available at: www.xfront.com/ExtendingSchemas.pdf
3. Costello, R. and Sperberg, R. (2001), “ISBN”. Available at: www.xfront.com/isbn.html
4. Flanagan, P. (1997), “The 10 hottest technologies in Telecom”, Telecommunications, May, pp. 25‐32.
5. Flynn, P. (1999), “Frequently asked questions about the Extensible Markup Language”. Available at: www.ucc.ie/xml/#SCHEMATA, June.