Radinka Dontcheva Masaaki Harada Some Extremal Self-Dual Codes with an Automorphism of Order 7. 75-79 2003 14 Appl. Algebra Eng. Commun. Comput. 2 http://dx.doi.org/10.1007/s00200-003-0126-4 db/journals/aaecc/aaecc14.html#DontchevaH03