@book{MSM_1928__28__1_0,
     author = {Cotton, \'Emile},
     title = {Approximations successives et \'equations diff\'erentielles},
     series = {M\'emorial des sciences math\'ematiques},
     publisher = {Gauthier-Villars},
     number = {28},
     year = {1928},
     language = {fr},
     url = {http://archive.numdam.org/item/MSM_1928__28__1_0/}
}