All flat manifolds are cusps of hyperbolic orbifolds
arXiv:math/0204238 · doi:10.2140/agt.2002.2.285
Abstract
We show that all closed flat n-manifolds are diffeomorphic to a cusp cross-section in a finite volume hyperbolic (n+1)-orbifold.
Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol2/agt-2-13.abs.html