Homology of closed geodesics in a negatively curvaed manifold
    Journal of Differential Geometry 26(1987), 81-96(no.1). [88g:58149]
        (with Toshikazu SUNADA)
Closed orbits of an Anosov flow and the fundamental group
    Proceedings of American Mathematical Society 100(1987), 595-598(no.3). [88j:58094]
K\"ahler magnetic flows on a manifold of constant holomorphic sectional curvature
    Tokyo Journal of Mathematics 18(1995), 473-483(no.2)
Holomorphic helices in a complex space form
    Proceedings of the American Mathematical Society 125(1997), 1197-1202(no.4)
        (with Sadahiro MAEDA)
A comparison theorem for magnetic Jacobi fields
    Proceedings of the Edinburgh Mathematical Society 40(1997), 293-308(no.2)
Length spectrum of geodesic spheres in a non-flat complex space form
    Journal of the Mathematical Society of Japan 54(2002), 373-408(no. 2, April)
        (with Sadahiro MAEDA and Masakazu Yamagishi)
A characterization of isotropic immersions by extrinsic shapes of smooth curves
    Differential Geometry and its Applications 26(2008), 307--312 (no.3)
        (with Tadashi SUGIYAMA)
Circular trajectories on real hypersurfaces in a nonflat complex space form,
    Journal of Geometry 96(2009), 41--55
        (with Bao TUYA)
A theorem of Hadamard-Cartan type for K\"ahler magnetic fields,