- Deadline: 23. Feb. 2009
- Scientific American 284(5):34-43 (2001)
- W3C Recommendation, W3C, (September 2007)
- W3C Recommendation, W3C, (January 2007)
- (2008)
- W3C Recommendation, World Wide Web Consortium, (1999)
- (2002)
- (November 2007)
- (2004)
- Comput. Netw. 31(11-16):1431--1451 (1999)
- (1997)
- (10 February 2004)
- (Mar 23, 2005)
- McGraw-Hill, (1985)


user