World Wide Web Consortiu http://www.w3c.org
Online XML Validator http://www.stg.brown.edu/service/xmlvalid/
Processing XML with Java http://www.ibiblio.org/xml/books/xmljava/
XML, CSS, XSLT, XML Schema, DTD slide-uri http://www.cis.upenn.edu/~matuszek/cit597-2002/
Extensible Markup Language (XML) 1.0 (Third Edition) W3C Recommendation 4th February 2004, François Yergeau, Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler
Elliotte Rusty Harold, XML Bible. IDG Books Worldwide, Inc, 919 E. Hillsdale Blvd., Suite 400, Foster City, CA 94404
Charles F. Goldfarb, Paul Prescod. The XML Handbook, Prentice Hall PTR, Upper Saddle River, NJ 07458, 2000
David Hunter, Andrew Watt, Jeff Rafter, Jon Duckett, Danny Ayers, Nicholas Chase, Joe Fawcett, Tom Gaven and Bill Patterson. Beginning XML, 3rd Edition, John Wiley & Sons Inc, September, 2004. isbn: 0-7645-7077-3