1. Montanet, L., Ross, G., Veneziano, G.: Phys. Rep.C63, 153 (1980) [contains a useful list of earlier references]
2. See, e.g., Seiden, A.: In: Proceedings of the XXIInd International Conference on High Energy Physics, Leipzig, German Democratic Republic, 1984
3. Review of Particie Properties, Phys. Lett.170B, 1 (1986)
4. Jaffe, R. L.: Phys. Rev.D17, 1444 (1978); Fukugita, M., et al.: Phys. Lett.B74, 261 (1978)
5. Chew, G., Rosenzweig, C.: Phys. Rep.C41, 263 (1978)