Ring class fields and a result of Hasse

R. Evans, F. Lemmermeyer, Z. -H. Sun +1

For squarefree $d>1$, let $M$ denote the ring class field for the order $Z[\sqrt{-3d}]$ in $F=Q(\sqrt{-3d})$. Hasse proved that $3$ divides the class number of $F$ if and only if t…