@article{ITA_1991__25_1_3_0,
     author = {Litovsky, I.},
     title = {Minimal generators of submonoids of $A^\infty $},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {3--17},
     publisher = {EDP-Sciences},
     volume = {25},
     number = {1},
     year = {1991},
     mrnumber = {1104407},
     zbl = {0725.68062},
     language = {en},
     url = {http://www.numdam.org/item/ITA_1991__25_1_3_0/}
}