@incollection{SB_1948-1951__1__71_0,
     author = {Cartan, Henri},
     title = {Les travaux de Koszul, III},
     booktitle = {S\'eminaire Bourbaki : ann\'ees 1948/49 - 1949/50 - 1950/51, expos\'es 1-49},
     author = {Collectif},
     series = {S\'eminaire Bourbaki},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {1},
     year = {1952},
     note = {talk:12},
     pages = {71-74},
     zbl = {0100.26201},
     mrnumber = {1605196},
     language = {fr},
     url = {http://www.numdam.org/item/SB_1948-1951__1__71_0}
}

Cartan, Henri. Les travaux de Koszul, III, in Séminaire Bourbaki : années 1948/49 - 1949/50 - 1950/51, exposés 1-49, Séminaire Bourbaki, no. 1 (1952), Talk no. 12, pp. 71-74. http://www.numdam.org/item/SB_1948-1951__1__71_0/