Fundamental Solutions and Eigenfunction Expansions for Schrödinger Operators . I. Fundamental Solutions. Hitoshi Kitada — 1988 Mathematische Zeitschrift
Fundamental Solutions and Eigenfunction Expansions for Schrödinger Operators. II. Eigenfunction Expansions. Arne Jensen; Hitoshi Kitada — 1988 Mathematische Zeitschrift
Bound states and scattering states for time periodic hamiltonians Kenji Yajima; Hitoshi Kitada — 1983 Annales de l'I.H.P. Physique théorique