CARLSON, David. Modeling XML vocabularies with UML. Part II. In: O'Reilly xml.com [online]. September 19, 2001 [cit. 2013-03-15]. Dostupné z: http://www.xml.com/pub/a/2001/09/19/uml.html.
Dostupné volně z: http://www.xml.com/pub/a/2001/09/19/uml.html.