1. Belavin, A. A., Polyakov, A. M., Schwarz, A. S., and Tyupkin, Yu. S. (1975). Pseudoparticle solutions of the Yang–Mills equations. Physics Letters B 59, 85–87.
2. Cheng, L.-P. and Li, L.-F. (1984). Gauge Theory of Elementary Particle Physics, Clarendon Press.
3. Chruściel, P. T. and Wald, R. M. (1994). On the topology of stationary black holes. Classical and Quantum Gravity 11, L147–L152.
4. Deser, S., Duff, M. J., and Isham, C. J. (1980). Gravitationally induced CP-effects. Physics Letters B 93, 419–423.
5. Etesi, G. (2001). The structure of Yang–Mills vacua seen by distant observers. In: Sidharth, B. G. and Altaisky, M. V. (Ed.), Consistent equation of classical gravitation to quantum limit and beyond. Kluwer Academic/Plenum Press Publishers, New York.