@article{SLC_1990_25_a13,
     author = {Giuseppe Pirillo},
     title = {Sul teorema di {Shirshov} e sui semigruppi ripetitivi},
     journal = {S\'eminaire lotharingien de combinatoire},
     year = {1990},
     volume = {25},
     url = {http://geodesic.mathdoc.fr/item/SLC_1990_25_a13/}
}