Groupes d'homotopie
Séminaire Bourbaki : années 1948/49 - 1949/50 - 1950/51, exposés 1-49, Séminaire Bourbaki no. 1  (1952), Talk no. 44, p. 365-370 
@incollection{SB_1948-1951__1__365_0,
     author = {Serre, Jean-Pierre},
     title = {Groupes d'homotopie},
     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:44},
     pages = {365-370},
     mrnumber = {1605158},
     language = {fr},
     url = {http://www.numdam.org/item/SB_1948-1951__1__365_0}
}

Serre, Jean-Pierre. Groupes d'homotopie, in Séminaire Bourbaki : années 1948/49 - 1949/50 - 1950/51, exposés 1-49, Séminaire Bourbaki, no. 1 (1952), Talk no. 44, pp. 365-370. http://www.numdam.org/item/SB_1948-1951__1__365_0/

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