@article{PPN362162808_0011+dmdlog6, title = {Some Free Submonoids of the Free Monoid of Prefix Codes.}, journal = {Semigroup forum}, volume = {11}, year = {1975}, pages = {22-29}, zbl = {0299.94005}, url = {http://dml.mathdoc.fr/item/PPN362162808_0011+dmdlog6} }
SHYR, H.J. Some Free Submonoids of the Free Monoid of Prefix Codes.. Semigroup forum, Tome 11 (1975) pp. 22-29. http://gdmltest.u-ga.fr/item/PPN362162808_0011+dmdlog6/