The official CSS page at the W3 Consortium.
The "Learn & Use" page is crammed full of links to tutorials, articles, and events. The majority of resources are in English, but there appear to be a decent number in other languages as well.
This document defines the syntax for specifying pronunciation lexicons to be used by Automatic Speech Recognition and Speech Synthesis engines in voice browser applications.
B. Klimek, N. Arndt, S. Krause, und T. Arndt. The 10th edition of the Language Resources and Evaluation Conference, 23-28 May 2016, Slovenia, Portorož, (2016)
D. Cowan, P. Alencar, F. McGarry, C. de Lucena, und I. Nunes. 2010 IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology, Seite 528-532. IEEE Computer Society, (2010)