@article{GDZPPN001260456,
title = {On the deficit of a set of words.},
journal = {Semigroup forum},
volume = {40},
year = {1990},
pages = {1-22},
zbl = {0679.20049},
url = {http://dml.mathdoc.fr/item/GDZPPN001260456}
}
Néraud, J. On the deficit of a set of words.. Semigroup forum, Tome 40 (1990) pp. 1-22. http://gdmltest.u-ga.fr/item/GDZPPN001260456/