@article{SF_1986__35_134868,
     author = {L. Zhang},
     title = {Rational strong codes and structure of rational group languages.},
     journal = {Semigroup forum},
     pages = {181--194},
     publisher = {mathdoc},
     volume = {35},
     year = {1986},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__35_134868/}
}