[By a theorem of L. Bieberbach](https://en.wikipedia.org/wiki/Flat_manifold) we know that that every closed flat Riemannian manifold is a quotient of a torus via action of a finite group $\Gamma$. In this question we are interested in the particular case of $3$ dimensional flat riemannian manifolds. So we assume that $(M,g)$ is a flat Riemannian $3$-manifold. then by above theorem we know that $(M,g)\cong T^3/\Gamma$, where $\Gamma$ is a finite group. **Questions** - Is there a complete classification of all finite group actions on flat $3$-torus which resulting quotion space would be a an orientable manifold with vanishing first Betti number or first integral homology? - According to Wikipedia Wiki(https://en.wikipedia.org/wiki/Flat_manifold), there is a complete list of all 6 orientable and 4 non-orientable flat compact manifolds. This list consists of all Seifert fiber spaces. Does the link of wikipedia actually means that all orientable Seifert Hyper spaces of dimension $4$ and $6$ have been classified? Any reference is welcome!