How have the courts dealt with improper references to prior convictions?

Although some type of unlawful argument by the government can be so prejudicial as to be incurable by any instruction, not all improper references to prior convictions are of this character. See Sumrall v. United States, 360 F.2d 311, 313-314 (10th Cir. 1966); United States v. Haskell, 217 F.Supp. 534, 543 (D.Conn.1963), aff'd, 327 F.2d 281 (2d Cir.), cert. denied, 377 U.S. 945, 84 S.Ct. 1351, 12 L.Ed.2d 307 (1964). Under the circumstances presented here, we conclude that the trial court's subsequent instructions were sufficient to cure the error. Appellant's conviction therefore is affirmed.