@Unpublished{K-theory/0663,
  author = 	 {{Baptiste Calmes}},
  title = 	 {{The group SK_2 of a biquaternion algebra}},
  note = 	 {{Preprint, September 2, 2003, K-theory Preprint Archives, http://www.math.uiuc.edu/K-theory/0663/}}}
}