Geometry & Topology Monographs Volume 14 (2008)

1	M Boileau, B Leeb, J Porti, Geometrization of 3–dimensional orbifolds, Ann. of Math. (2) 162 (2005) 195–290 MR2178962
2	M Boileau, J Porti, Geometrization of 3–orbifolds of cyclic type, Astérisque (2001) 208 MR1844891 Appendix A by Michael Heusener and Porti
3	D Burago, Y Burago, S Ivanov, A course in metric geometry, Graduate Studies in Mathematics 33, American Mathematical Society (2001) MR1835418
4	Y Burago, M Gromov, G Perel'man, A D Aleksandrov spaces with curvatures bounded below, Uspekhi Mat. Nauk 47 (1992) 3–51, 222 MR1185284
5	J Cheeger, D Gromoll, On the structure of complete manifolds of nonnegative curvature, Ann. of Math. (2) 96 (1972) 413–443 MR0309010
6	D Cooper, C D Hodgson, S P Kerckhoff, Three-dimensional orbifolds and cone-manifolds, MSJ Memoirs 5, Mathematical Society of Japan (2000) MR1778789 With a postface by Sadayoshi Kojima
7	M Culler, Lifting representations to covering groups, Adv. in Math. 59 (1986) 64–70 MR825087
8	L Guijarro, V Kapovitch, Restrictions on the geometry at infinity of nonnegatively curved manifolds, Duke Math. J. 78 (1995) 257–276 MR1333500