1. A. Vilenkin, P.S. Shellard, Cosmic String and Other Topological Defects, Cambridge Univ. Press, 1993.
2. E. Kroner, Continuum theory of Defects, course 3, in: Physics of Defects, Les Houches Session XXXV, North-Holland, Amsterdam, 1981.
3. P.S. Letelier, J. Math. Phys., 1995.
4. Spacetime defects: torsion loops
5. Spacetime defects: Domain walls and torsion