@article{CMH_1956__30_139122,
     author = {Gabriel Thierrin},
     title = {Sur la th\'eorie des demi-groupes.},
     journal = {Commentarii mathematici Helvetici},
     pages = {211--223},
     publisher = {mathdoc},
     volume = {30},
     year = {1956},
     zbl = {0070.01802},
     url = {http://geodesic.mathdoc.fr/item/CMH_1956__30_139122/}
}