@incollection{AST_2004__296__253_0,
     author = {Umemura, Hiroshi},
     title = {Monodromy preserving deformation and differential {Galois} group {I}},
     booktitle = {Analyse complexe, syst\`emes dynamiques, sommabilit\'e des s\'eries divergentes et th\'eories galoisiennes (I) - Volume en l'honneur de Jean-Pierre Ramis},
     editor = {Loday-Richaud Mich\`ele},
     series = {Ast\'erisque},
     pages = {253--269},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {296},
     year = {2004},
     mrnumber = {2136013},
     zbl = {1159.12313},
     language = {en},
     url = {http://www.numdam.org/item/AST_2004__296__253_0/}
}