\title{The group of endotrivial modules in the normal case}
\author{Nadia Mazza}
\address{Department of Mathematics, University of Georgia, Athens, GA~30602, USA}

Abstract: The group of endotrivial modules has recently been determined for a finite group having a normal Sylow $p$-subgroup. In this paper, we give and compare three different presentations of a torsion-free subgroup of maximal rank of the group of endotrivial modules. Finally, we illustrate the constructions in an example.

Keywords: Endotrivial modules, finite groups, cohomology of finite groups.

Status: to appear.