The RDDL Specification: http://www.rddl.org/ (Written in RDDL)
RDDL Me This: http://xml.oreilly.com/news/xmlnut2_0201.html
XML Bible, Gold edition
Elliotte Rusty Harold
Hungry Minds, 2001
ISBN 0-7645-3597-8
XLinks: http://www.cafeconleche.org/books/bible2/chapters/ch19.html