Chris Lilley; T. V. Raman. <a href="http://www.w3.org/TR/1999/WD-acss-19990902"><cite>Aural Cascading Style Sheets (ACSS) Specification.</cite></a> 2 September 1999. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/1999/WD-acss-19990902">http://www.w3.org/TR/1999/WD-acss-19990902</a>