@article{GDZPPN001261541,
title = {Inverse monoids and rational Schreier subsets of the free group.},
journal = {Semigroup forum},
volume = {44},
year = {1992},
pages = {137-148},
zbl = {0757.20017},
url = {http://dml.mathdoc.fr/item/GDZPPN001261541}
}
Margolis, S.; Meakin, C.J. Inverse monoids and rational Schreier subsets of the free group.. Semigroup forum, Tome 44 (1992) pp. 137-148. http://gdmltest.u-ga.fr/item/GDZPPN001261541/