[XML98] World Wide Web Consortium, Tim Bray, Jean Paoli, and Michael Sperberg-McQueen. Extensible Markup Language (XML) 1.0. See also the annotated version of the XML specification..

[TDG1999] Norman Walsh and Leonard Muellner. Docbook. The Definitive Guide.. O'Reilly & Associates, Inc.. Copyright © 1999. 1-56592-580-7. Oreilly's catalog entry. . You can also consult the online version of the DocBook reference guide and download the Docbook DTD and XSL stylesheets..

[MATHML2] World Wide Web Consortium, David Carlisle, Patrick Ion, Robert Miner, and Nico Poppelier. Mathematical Markup Language (MathML) Version 2.0 .