@incollection{AST_1977__41-42__247_0,
     author = {Oriat, Bernard},
     title = {Relations entre les $2$-groupes des classes d'id\'eaux de $k (\sqrt{d})$ et $k (\sqrt{-d})$},
     booktitle = {Journ\'ees arithm\'etiques de Caen},
     series = {Ast\'erisque},
     pages = {247--249},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {41-42},
     year = {1977},
     zbl = {0348.12007},
     mrnumber = {506162},
     language = {fr},
     url = {http://archive.numdam.org/item/AST_1977__41-42__247_0/}
}