1. Experimental Observation of a Heavy ParticleJ
2. Discovery of a Narrow Resonance ine+e−Annihilation
3. Discovery of a Second Narrow Resonance ine+e−Annihilation
4. For recent reviews of the theory of heavy QQ̄ bound states, and extensive references, see: K. Gottfried, Cornell Univ. preprint CLNS-376, to be published in Proc. 1977 Intern. Symp. on Lepton and photon interactions at high energy (Hamburg);
5. Quark confinement and field theory;Yan,1977