1. Kip S. Thorne, Nonspherical Gravitational Collapse: A Short Review in Magic without Magic, edited by J. Klauder (Freeman, San Francisco, 1972)
2. S. Dimopoulos, G.L. Landsberg, Phys. Rev. Lett. 87, 161602 (2001) arXiv:hep-ph/0106295
3. S.B. Giddings, S.D. Thomas, Phys. Rev. D 65, 056010 (2002) arXiv:hep-ph/0106219
4. Thomas F. Gallagher, Rydberg Atoms, in Cambridge Monographs on Atomic, Molecular and Chemical Physics (Cambridge University Press, 1994)
5. L. Holmlid, JETP 100, 637 (2005)