1. A course in simple-homotopy theory;Cohen,1973
2. Construction of group actions on four-manifolds;Edmonds;Trans. Amer. Math. Soc.,1987
3. 3-manifolds;Hempel,1976
4. A course in homological algebra;Hilton,1970
5. E. Luft and D. Sjerve, On regular coverings of 3-manifolds by homology 3-spheres, to appear.