On essential self-adjointness of the relativistic hamiltonian of a spinless particle in a negative scalar potential Wataru Ichinose — 1994 Annales de l'I.H.P. Physique théorique
On the semi-classical approximation of the solution of the Heisenberg equation with spin Wataru Ichinose — 1997 Annales de l'I.H.P. Physique théorique