XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML documents, or other objects such as HTML for web pages, plain text or into XSL Formatting Objects which can then be converted to PDF, PostScript and PNG.

XSLT :programmer's reference
XSL Transformations (XSLT) 1.0
XSL Transformations (XSLT) Version1.0
XSL Transformations (XSLT) Version 1.0
XSL Transformations (XSLT) version 2.0
A proof of the Turing-completeness of XSLT and XQuery
A formal model for an expressive fragment of XSLT
Rendering an HTML electronic form by applying XSLT to XML using a solution
XSPARQL: traveling between the XML and RDF worlds - and avoiding the XSLT pilgrimage
First experiments with the ATL model transformation language: Transforming XSLT into XQuery