text: * Clancy, L.J. (1975), Aerodynamics, Pitman Publishing Limited, London 
  * "[https://web.archive.org/web/20060427140337/http://www.weather.com/glossary/v.html Weather Glossary]"' The Weather Channel Interactive, Inc.. 2004.
  * "[http://www.tpub.com/content/aerographer/14010/css/14010_18.htm Vorticity]". Integrated Publishing.