Papers on Fermat's congruence by Hans Riesel
Note on the congruence a^(p-1)=1 (mod p^2),
Math.Comp.
18
(1964) pp. 149-150.
Some soluble cases of the discrete logarithm problem,
BIT
28
(1988) pp. 839-851.
Upp till
Riesels hemsida
.