United States v. Sarbia, 367 F.3d 1079 (9th Cir. May 14, 2004) (in defining "crime of violence" per U.S.S.G. 4B1.2, there is not difference between commission and attempted commission of an offense).
http://caselaw.lp.findlaw.com/data2/circs/9th/0310276p.pdf