Mass formula and structure of self-dual codes over (with K.Nagata, F.Nemenzo), to appear in Designs, Code and Cryptography (2012)
On efficient computation of the 2-parts of ideal class groups of quadratic fields (with J. M. Basilla), Proc. Japan Acad. Ser. A Math. Sci. 80 (2004), no.10, 191-193
On the Diophantine equation , Proc. Japan Acad. Ser. A Math. Sci. 79 (2003), no. 5, 99-100
"Hasse principle" for free groups (with T. Ono), Proc. Japan Acad. Ser. A Math. Sci. 75 (1999), no.1, 1-2
素因子分解とコンピュータ, 数学, 38 (1986), no. 4, 345-350
A remark on the \lambda -invariant of real quadratic fields (with T. Fukuda, K. Komatsu), Proc. Japan Acad. Ser. A Math. 62(1986), no.8, 318-319
A note on the Pell equation, Tokyo J. Math. 2(1979), no. 1, 133-136
Diophantine representation of the set of prime numbers (with J. P. Jones, D. Sato, D. Wiens), Amer. Math. Monthly 83(1976), no. 6, 449-464
整数論と計算機について, 数学 26(1974), no. 3, 193-200
On cubic Galois extensions of , Proc. Japan Acad. 46(1970), 397-400
On the class number and the unit group of certain algebraic number fields, J. Fac. Sci. Univ. Tokyo Sect. I 13(1966), 201-209