@incollection{SB_1978-1979__21__170_0,
     author = {Oesterl\'e, Joseph},
     title = {Travaux de {Ferrero} et {Washington} sur le nombre de classes d'id\'eaux des corps cyclotomiques},
     booktitle = {S\'eminaire Bourbaki : vol. 1978/79, expos\'es 525-542},
     series = {S\'eminaire Bourbaki},
     note = {talk:535},
     pages = {170--182},
     publisher = {Springer-Verlag},
     number = {21},
     year = {1980},
     mrnumber = {572424},
     zbl = {0436.12003},
     language = {fr},
     url = {http://www.numdam.org/item/SB_1978-1979__21__170_0/}
}