DTD - tutoriály

Webreview: http://www.webreview.com/2000/08_11/developers/08_11_00_2.shtml

ZVON: http://www.zvon.org/xxl/DTDTutorial/General/contents.html

XML DTD Tutorial (101): http://www.xml101.com/dtd/

W3Schools DTD Tutorial: http://www.w3schools.com