@Unpublished{K-theory/0102,
  author = 	 {{Alejandro Adem and Max Karoubi}},
  title = 	 {{Periodic Cyclic Cohomology of Group Rings}},
  note = 	 {{Preprint, February 1, 1996, K-theory Preprint Archives, http://www.math.uiuc.edu/K-theory/0102/}}}
}