XML Schema Reference at Zvon
- A complete hyperlinked reference for XML Schema which can be downloaded for offline use.
- http://www.zvon.org/xxl/xmlSchema2001Reference/Output/index.html

W3C XML Schema Test Collection
- Collection of test schemas used to ensure consistency among XML Schema implementations.
- http://www.w3.org/2001/05/xmlschema-test-collection.html

W3C Official Public Site for XML Schema
- Contains status information, links to specifications and tools that implement XML Schema
- http://www.w3.org/XML/Schema