1. Heckman, H.H.: Proc. of the 5th Int. Conf. on High-Energy Physics and Nuclear Structure, Uppsala 1973, (G. Tibell ed.) p. 403. Amsterdam: North-Holland Publ. Comp. 1974
2. Feshbach, H., Huang, K.: Phys. Lett.47 B, 300 (1973)
3. Goldhaber, A.S.: Phys. Lett.53 B, 306 (1974)
4. Greiner, D.E., Lindstrom, P.J., Heckman, H.H., Cork, B., Bieser, F.S.: Phys. Rev. Lett.35, 152 (1975)
5. Jakobson, B., Kullberg, R., Otterlund, I.: Presented at the 6th Int. Conf. on High-Energy Physics and Nuclear Structure, Santa Fe 1975