BibTeX Reference for “Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification”

@TechReport{9311526,
  author      = "Tantek \c{C}elik and Ian Hickson and H\aa{}kon Wium Lie and Bert Bos",
  title       = "Cascading Style Sheets Level 2 Revision 1 ({CSS} 2.1) Specification",
  month       = jun,
  note        = "https://www.w3.org/TR/2011/REC-CSS2-20110607/",
  year        = "2011",
  bibsource   = "https://w2.syronex.com/jmr/w3c-biblio",
  type        = "{W3C} Recommendation",
  institution = "W3C",
}