@article{preprint-voloch
,note={URL: {\tt http://www.ma.utexas.edu/users/voloch/preprint.html}. Note: to appear}
,author={Jos\'e Felipe Voloch}
,ISSN={1246--7405}
,journal={Journal de Th\'eorie des Nombres de Bordeaux}
,title={{On some subgroups of the multiplicative group of finite rings}}
}