@article{CMH_1946__19_138896,
     author = {Sophie Piccard},
     title = {Des syst\`emes de substitutions reguli\`eres ind\'ependantes qui engendrent un groupe r\'egulier.},
     journal = {Commentarii mathematici Helvetici},
     pages = {134--152},
     publisher = {mathdoc},
     volume = {19},
     year = {1946},
     zbl = {0061.03204},
     url = {http://geodesic.mathdoc.fr/item/CMH_1946__19_138896/}
}