Date: Jun. 10, 1999
Link: http://www.pault.com/Xmltube/dtdgen.html
Source Author or Organization: XML Tube

This is Michael Kay's Java-based DTD Generator attached to a frontend (a Python script by Paul Tchistopolski) in an easy to use online version.

DTD Generator derives the structure of the DTDs it generates using the structure of an XML document you feed to it. Just go to the url above and type in the name of an XML file residing locally on your hard drive.