1. Connes, A., Douglas, M., Schwarz, A.S.: J. High Energy Phys. 9802, 003 (1998)
2. Seiberg, N., Witten, E.: J. High Energy Phys. 09, 032 (1999)
3. Chu, C., Ho, P.: Nucl. Phys. B 550, 151 (1999). hep-th/9812219
4. Gopakumar, R., Maldacena, J., Minwalla, S., Strominger, A.: J. High Energy Phys. 0006, 036 (2000)
5. Chaichian, M., Sheikh-Jabbari, M.M., Tureanu, A.: Phys. Rev. Lett. 86, 2716 (2001). hep-th/0010175