@article{SF_1986__35_134856,
     author = {J.E. Pin},
     title = {A property of the {Sch\"utzenberger} product.},
     journal = {Semigroup forum},
     pages = {53--62},
     publisher = {mathdoc},
     volume = {35},
     year = {1986},
     zbl = {0618.20040},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__35_134856/}
}