%0 Journal Article %A Smith, D. H. %T Perfect codes in the graphs Ok and L(Ok) %J Glasgow mathematical journal %D 1980 %P 169-172 %V 21 %N 1 %U http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004146/ %R 10.1017/S0017089500004146 %F 10_1017_S0017089500004146