A criterion for the class number of a pure quintic field to be divisible by 5. Kiyoaki Iimura — 1977 Journal für die reine und angewandte Mathematik
On the l-class group of an algebraic number field. Kiyoaki Iimura — 1981 Journal für die reine und angewandte Mathematik
Dihedral extensions of Q of degree 21 which contain non-Galois extensions with class number not divisible by l Kiyoaki Iimura — 1979 Acta Arithmetica