@article{IM_1981__65_142864,
     author = {Toshinori \^Oaku},
     title = {A {Canonical} {Form} of a {System} of {Microdifferential} {Equations} with {Non-Involutory} {Characteristics} and {Branching} of {Singularities.}},
     journal = {Inventiones mathematicae},
     pages = {491--525},
     publisher = {mathdoc},
     volume = {65},
     year = {1981},
     zbl = {0493.35083},
     url = {http://geodesic.mathdoc.fr/item/IM_1981__65_142864/}
}