@article{SF_1980__20_134401,
     author = {J.E. Pin},
     title = {Varietes de languages et monoide des parties.},
     journal = {Semigroup forum},
     pages = {11--48},
     publisher = {mathdoc},
     volume = {20},
     year = {1980},
     zbl = {0451.20061},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__20_134401/}
}