@Unpublished{K-theory/1008,
  author = 	 {{Matilde Marcolli and Goncalo Tabuada}},
  title = 	 {{Kontsevich's category of noncommutative numerical motives.}},
  note = 	 {{Preprint, August 18, 2011, K-theory Preprint Archives, http://www.math.uiuc.edu/K-theory/1008/}}}
}