Contractible open 3-manifolds which non-trivially cover only non-compact 3-manifolds
Citation
Myers, R. (1999). Contractible open 3-manifolds which non-trivially cover only non-compact 3-manifolds. Topology, 38(1), pp. 85-94. https://doi.org/10.1016/S0040-9383(98)00004-4