@article{JRAM_1972__252_151187,
     author = {Masatoshi Ikeda},
     title = {A generalization of the {Hasse-Arf} theorem.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {183--186},
     publisher = {mathdoc},
     volume = {252},
     year = {1972},
     zbl = {0237.12009},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1972__252_151187/}
}