@article{MZ_1977__154_172515,
     author = {J\'anos Acz\'el},
     title = {Functions of {Binomial} {Type} {Mapping} {Groupoids} into {Rings.}},
     journal = {Mathematische Zeitschrift},
     pages = {115--124},
     year = {1977},
     volume = {154},
     zbl = {0335.39007},
     url = {http://geodesic.mathdoc.fr/item/MZ_1977__154_172515/}
}