Read at the annual meeting of physical society of Japan held at Tokyo University on May 2. 1949. Vacuum polarization.

Read at the Symposium on the theory of Elementary Particles at Kyoto, Japan, May 1948. Vacuum polarization.

Read at the annual meeting of physical society of Japan held at Tokyo University on May 2. 1949. Dirac particle, relativistic covariance.

Formulae relating to vacuum polarization.

Read at the annual meeting of physical society of Japan held at Tokyo University, on May 2, 1949. Perturbation theory.