@incollection{AST_1985__126__169_0,
     author = {Bourguignon, Jean-Pierre},
     title = {Groupes d'holonomie des varietes riemanniennes},
     booktitle = {G\'eom\'etrie des surfaces $K3$ : modules et p\'eriodes - S\'eminaire Palaiseau},
     series = {Ast\'erisque},
     pages = {169--180},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {126},
     year = {1985},
     mrnumber = {785233},
     zbl = {0559.53034},
     language = {fr},
     url = {http://www.numdam.org/item/AST_1985__126__169_0/}
}