1. M. Atiyah, N. Hitchin, V. Drinfeld, and Yu. Manin, Phys. Lett. 65A (1978) 185.
2. E. Corrigan, D. Fairlie, P. Goddard,and S. Templeton, Nucl. Phys. B140 (1978)31.
3. W. Nahm, in:.Group Theoretical Methods in Physics, M. Serdaroglu et al. eds., Istanbul 1982, p.456.
4. W. Nahm, in: Monopoles in Quantum Field Theory, N. Craigie et al. eds., Trieste 1981, p.87.
5. N. Hitchin, Comm. Math. Phys. 89 (1983) 145.