[1] L. Skula: Special invariant subspaces of a vector space over Z/lZ. Archivum Math. Brno, to appeaг. Zbl 0737.11027

[2] S. S. Wagstaff, Jr.: The irregular primes to 125,000. Math. Comp. 32 (1978), 583-591; the more detailed results in personal communication to L. Skula. MR 0491465

[3] L. C. Washington: Introduction to Cyclotomic Fields. Spгinger-Veгlag, New Yoгk,. Heidelbeгg, Berlín, 1982. MR 0718674 | Zbl 0484.12001