@article{MZ_1992__210_1_174404,
     author = {Michael Voit},
     title = {Duals of subhypergroups and quotients of commutative hypergroups.},
     journal = {Mathematische Zeitschrift},
     pages = {289--304},
     publisher = {mathdoc},
     volume = {210},
     number = {1},
     year = {1992},
     zbl = {0759.43002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1992__210_1_174404/}
}