@incollection{AST_1983__98-99__184_0,
     author = {Sim\'o, Carles},
     title = {Stability of degenerate fixed points of analytic area preserving mappings},
     booktitle = {Bifurcation, th\'eorie ergodique et applications - 22-26 juin 1981},
     series = {Ast\'erisque},
     pages = {184--194},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {98-99},
     year = {1982},
     mrnumber = {724447},
     zbl = {0516.58028},
     language = {en},
     url = {http://archive.numdam.org/item/AST_1983__98-99__184_0/}
}