Iwan M. Duursma Ruud Pellikaan A symmetric Roos bound for linear codes. 1677-1688 2006 113 J. Comb. Theory, Ser. A 8 http://dx.doi.org/10.1016/j.jcta.2006.03.020 db/journals/jct/jcta113.html#DuursmaP06