Schematron reference at Zvon - A complete reference for Schematron with examples. www.zvon.org/ZvonSW/ZvonSchematron/Reference/Output/index.html
Schematron Specification - A tree-pattern schema language, assertion-based rather than grammar-based, built on top of XSLT with XPath. www.ascc.net/xml/resource/schematron/schematron.html
Schematron Tutorial at Zvon - A tutorial for Schematron with many examples. www.zvon.org/xxl/SchematronTutorial/General/contents.html
Topologi Schematron Validator - Shareware that validates XML documents using Schematron, DTDs, and W3C XML Schemas www.topologi.com/validator