Reference:
 - Author: Brendan J. Frey and Delbert Dueck
   Title: Clustering by Passing Messages Between Data Points
   Journal: Science
   Day: 6
   Month: 2
   Year: 2007
   Volume: 315
   Number: 5814
   Pages: 972-976
   DOI: 10.1126/science.1136800
   URL: http://science.sciencemag.org/content/315/5814/972.full
