%0 Journal Article %T Ray Class Groups of Quadratic and Cyclotomic Fields %A Jing Long Hoelscher %J Mathematics %D 2008 %I arXiv %X This paper studies Galois extensions over real quadratic number fields or cyclotomic number fields ramified only at one prime. In both cases, the ray class groups are computed, and they give restrictions on the finite groups that can occur as such Galois groups. Also the explicit structure of ray class groups of regular cyclotomic number field is given. %U http://arxiv.org/abs/0810.4740v2