@article{AUCMP_1987_28_1_a3,
     author = {Vougiouklis, Th. and Konguetsof, L.},
     title = {$P$-hypergoupes},
     journal = {Acta Universitatis Carolinae. Mathematica et Physica},
     pages = {15--20},
     year = {1987},
     volume = {28},
     number = {1},
     mrnumber = {0929262},
     zbl = {0658.20044},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUCMP_1987_28_1_a3/}
}