1. 1) Nakaya, U. and Terada, T. Jr. J., 1935: J. Fac. of Sci., Hokkaidô Univ., Ser. II, Vol. I, No.7, pp. 191-200.
2. 2) Nakaya, U. and Sekido, Y., 1931: J. Fac. of Sci., Hokkaidô Univ., Ser. II, Vol. I, No.9, pp. 243-264.
3. 6) Arakawa, K. and Higuchi, K., 1952: J. Fac. of Sci., Hokkaidô Univ., Ser. II, Vol. IV, No.3, pp. 201-208.