Déterminations des corps $K = mathbb Q(\surdd, \surd −1)$ dont les 2-groupes de classes sont de type (2, 4) ou (2, 2, 2)

Let d be a square-free positive integer, $K = mathbb Q(\surdd, \surd −1)$ and C2 the 2-part of class group of K. Our goal is to determine all d such that $C2 \simeq Z/2Z \times Z/4Z$ or $C2 \simeq Z/2Z \times Z/2Z \times Z/2Z$.