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@article{MV_1969_21_4_a19, author = {R. Daci\'c}, title = {Group and hypergroup operations induced by multivalued functions}, journal = {Matemati\v{c}ki vesnik}, pages = {463 }, publisher = {mathdoc}, volume = {21}, number = {4}, year = {1969}, url = {http://geodesic.mathdoc.fr/item/MV_1969_21_4_a19/} }
R. Dacić. Group and hypergroup operations induced by multivalued functions. Matematički vesnik, Tome 21 (1969) no. 4, p. 463 . http://geodesic.mathdoc.fr/item/MV_1969_21_4_a19/