@article{SD_1962-1963__16_1_A9_0,
     author = {Koskas, Maurice},
     title = {Contribution \`a l'\'etude des groupo{\"\i}des. {Demi-hypergroupes}},
     journal = {S\'eminaire Dubreil. Alg\`ebre et th\'eorie des nombres},
     note = {talk:9},
     pages = {1--26},
     publisher = {Secr\'etariat math\'ematique},
     volume = {16},
     number = {1},
     year = {1962-1963},
     zbl = {0272.20055},
     language = {fr},
     url = {http://www.numdam.org/item/SD_1962-1963__16_1_A9_0/}
}