@article{SLC_1986_15_a14,
     author = {Giuseppe Pirillo},
     title = {Sulle propriet\`a {P} e {P*} nei semi-gruppi},
     journal = {S\'eminaire lotharingien de combinatoire},
     publisher = {mathdoc},
     volume = {15},
     year = {1986},
     url = {http://geodesic.mathdoc.fr/item/SLC_1986_15_a14/}
}