@article{1256067893,
author = {Ginsburg, Seymour and Hibbard, Thomas N. and Ullian, Joseph S.},
title = {Sequences in context free languages},
journal = {Illinois J. Math.},
volume = {9},
number = {4},
year = {1965},
pages = { 321-337},
language = {en},
url = {http://dml.mathdoc.fr/item/1256067893}
}
Ginsburg, Seymour; Hibbard, Thomas N.; Ullian, Joseph S. Sequences in context free languages. Illinois J. Math., Tome 9 (1965) no. 4, pp. 321-337. http://gdmltest.u-ga.fr/item/1256067893/