@article{COMIM_1996__4_1_a9,
     author = {Chvalina, Jan and Chvalinov\'a, Ludmila},
     title = {State hypergroups of automata},
     journal = {Communications in Mathematics},
     pages = {105--119},
     publisher = {mathdoc},
     volume = {04},
     number = {1},
     year = {1996},
     mrnumber = {1446788},
     zbl = {0870.20053},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/COMIM_1996__4_1_a9/}
}