@article{M2AN_1969__3_2_51_0,
     author = {Boucher, Claude},
     title = {Fermeture de certaines classes de langages formels sous des permutations linguistiques},
     journal = {ESAIM: Mathematical Modelling and Numerical Analysis },
     pages = {51--61},
     publisher = {Dunod},
     address = {Paris},
     volume = {3},
     number = {R2},
     year = {1969},
     mrnumber = {272562},
     zbl = {0209.31001},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/M2AN_1969__3_2_51_0/}
}