Helvering v. National Grocery Co. , 58 S. Ct. 932 ( 1938 )
birmingham-business-college-inc-john-ike-griffith-hulon-a-spears-and , 276 F.2d 476 ( 1960 )
Commissioner v. Duberstein , 80 S. Ct. 1190 ( 1960 )