On the space curves with the same dual varietey. Hajime Kaji — 1993 Journal für die reine und angewandte Mathematik
On the space curves with the same image under the Gauss maps. Hajime Kaji — 1993 Manuscripta mathematica
On the inseparable degrees of the Gauss map and the projection of the conormal variety to the dual fo higher order for space curves. Hajime Kaji — 1992 Mathematische Annalen
On the generic injectivity of the Gauss map in positive characteristic. Hajime Kaji; Atsushi Noma — 1997 Journal für die reine und angewandte Mathematik