1. Proceedings of the 4th Moriond Workshop on Massive Neutrino in Particle and Astrophysics;Kotani,1984
2. W.C. Haxton and G.J. Stephenson Jr., Los Alamos preprint LA-UR-84-396.
3. M. Doi et al., Osaka University preprint .
4. Double Beta Decay
5. The Energy Spectrum and the Angular Correlation in the Decay