d 917, 923 (E.D.Ark.2006) ("In a diversity case, the Court applies federal law to re- solve work product claims."); Bank of the West Valley Nat. Bank of Ariz., 132 F.R.D. 250 (N.D.Ca1.1990) (in diversity action, California law would govern res- olution of issues arising out of plaintiffs invocation of at