1. N. Isgur, “Proceedings of Glueballs, Hybrid and Exotic Hadrons” Conf., Brookhaven Nat. Lab., 3 (1988).
2. F. Close, 421, same proceedings.
3. Walter Toki, 692, same proceedings.
4. S. Godfrey and H. Willutzki, 703, same proceedings.
5. R. Huff and J. Kirz, Lawrence Rad. Lab. Phys. Note 474, taken from R. D. Tripp Ann. Rev. Nucl. Part. 15:325 (1965).