@article{SF_1983__26_134614,
     author = {J.C. Spehner},
     title = {Sur la classification syntaxique.},
     journal = {Semigroup forum},
     pages = {323--348},
     publisher = {mathdoc},
     volume = {26},
     year = {1983},
     zbl = {0514.20052},
     url = {http://geodesic.mathdoc.fr/item/SF_1983__26_134614/}
}