Jensen and Yui (Polynomials with D_p as Galois group J. Number Theory 15, 347-375 (1982)) proved that if p = 4n+1 is a regular prime, then there is no normal extension of the rationals with Galois group D_p (dihedral of order 2p) ramified only at p. When I first read it I noticed that such an extension exists if and only if p divides u, where $t+u\sqrt{p}$ is the fundamental unit of the real quadratic number field with discriminant p (Ankeny, Artin and Chowla conjectured that this never happens; it is known that this property is equivalent to the divisibility of the Bernoulli number B_(p-1)/2 by p, hence implies that p is irregular).

I recall having seen this result in print a few years later, but can't find it anymore. Can anyone help me?

Jensen and Yui (Polynomials with $D_p$ as Galois group J. Number Theory 15, 347–375 (1982)) proved that if $p = 4n+1$ is a regular prime, then there is no normal extension of the rationals with Galois group $D_p$ (dihedral of order $2p$) ramified only at $p$. When I first read it I noticed that such an extension exists if and only if $p$ divides $u$, where $t+u\sqrt{p}$ is the fundamental unit of the real quadratic number field with discriminant $p$ (Ankeny, Artin and Chowla conjectured that this never happens; it is known that this property is equivalent to the divisibility of the Bernoulli number $B_{(p-1)/2}$ by $p$, hence implies that $p$ is irregular).

I recall having seen this result in print a few years later, but can't find it anymore. Can anyone help me?