@book{AST_2012__341__1_0,
     author = {Delort, Jean-Marc},
     title = {A quasi-linear {Birkhoff} normal forms method. {Application} to the quasi-linear {Klein-Gordon} equation on $\mathbb{S}^1$},
     series = {Ast\'erisque},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {341},
     year = {2012},
     mrnumber = {2952065},
     zbl = {1243.35123},
     language = {en},
     url = {http://archive.numdam.org/item/AST_2012__341__1_0/}
}