@article{KYB_1973_9_6_a2,
     author = {Cremers, A. B. and Weiss, K.},
     title = {Some further remarks on the index of context-free languages},
     journal = {Kybernetika},
     pages = {461--466},
     year = {1973},
     volume = {9},
     number = {6},
     mrnumber = {0395341},
     zbl = {0278.68075},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1973_9_6_a2/}
}