@incollection{AST_1980__80__21_0,
     author = {Bourguignon, Jean-Pierre},
     title = {D\'eformations des m\'etriques {d'Einstein}},
     booktitle = {Analyse sur les vari\'et\'es (Metz, 1979)},
     series = {Ast\'erisque},
     pages = {21--31},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {80},
     year = {1980},
     mrnumber = {620167},
     zbl = {0473.53040},
     language = {fr},
     url = {http://www.numdam.org/item/AST_1980__80__21_0/}
}