1. Nielsen, H. B., Ninomiya, M.: Nucl. Phys.B185, 20 (1981)
2. Nielsen, H. B., Ninomiya, M.: Niels Bohr Institute preprint, January 1981
3. Kogut, J., Susskind, L.: Phys. Rev.D11, 395 (1975)
4. Swann, R. G.: Trans. Am. Math. Soc.237, 111 (1978)
5. See for example Kobayashi, S., Nomizu, K.: Foundations of Differential Geometry Vol. II, New York: Interscience 1969