@book{SB_1980-1981__23_, author = {Collectif}, title = {S\'eminaire {Bourbaki} : vol. 1980/81, expos\'es 561-578}, series = {S\'eminaire Bourbaki}, publisher = {Springer-Verlag}, number = {23}, year = {1981}, url = {http://archive.numdam.org/item/SB_1980-1981__23_/} }