1. Alvarez, E. 1984,Phys. Rev.,D30, 394; Errata: 1984,Phys. Rev.,D30, 2695.
2. Bais, F. A., Nicolai, H., van Nieuwenhuizen, P. 1983,Nucl. Phys.,B288, 333.
3. Barrow, J. D. 1981,Phys. Rev. Lett.,46, 963; Errata: 1981,Phys. Rev. Lett.,46, 1436.
4. Barrow, J. D. 1982,Phys. Rep.,85, 1.
5. Barrow, J. D. 1984, inClassical General Relativity, Eds W. B. Bonnor, J. N. Isham & M. A. H. MacCallum, Cambridge Univ. Press.