To reference POV-Ray (e.g. in academic papers), you may use one of the below:

  Persistence of Vision Pty. Ltd. (2004)
    Persistence of Vision Raytracer (Version 3.6)
    [Computer software].
      Retrieved from http://www.povray.org/download/

or

 
  Persistence of Vision Pty. Ltd. (2004).
  Persistence of Vision (TM) Raytracer.
  Persistence of Vision Pty. Ltd., Williamstown, Victoria, Australia.
   http://www.povray.org/

2.5.1 POV-Ray User License

2.5.2 Citing POV-Ray in Academic Publications

2.5.3 The POV-Team