1. On the associative functional equations and a characterization of general linear spaces by the mixture rule;Kitagawa;Japan J. Math.,1936
2. On the theory of linear translatable functional equations and Cauchy's series;Kitagawa;Japan. J. Math.,1937
3. The characterizations of the functional linear operations by means of the operational equations;Kitagawa;Mem. Fac. Sci. Kyushu Univ.,1940
4. The limit theorems of the stochastic contagious processes;Kitagawa;Mem. Fac. Sci. Kyushu Univ.,1940
5. The weakly contagious discrete stochastic process;Kitagawa;Mem. Fac. Sci. Kyushu Univ.,1941