1. Particle Data Group, Phys.Rev. D 54 (1996) 1–720. Updates can be found at: http://www-pdg.lbl.gov/
2. For recent reviews see, for example: Proc. of the Int. Workshop on Double Beta Decay and Related Topics, Trento, Italy, April 24–May 5, 1995, ed. by H.V. Klapdor-Kleingrothaus and S. Stoica, World Scientific, Singapore, 1996
3. H.V. Klapdor-Kleingrothaus, Proc. NEUTRINO’96, Helsinki, June 1996, World Scientific, Singapore, 1997, p. 317
4. H.V. Klapdor-Kleingrothaus, Proc. of the Int. Conf. Beyond the Desert, June 8–14, 1997, Castle Ringberg, Germany, eds. H.V. Klapdor-Kleingrothaus and H. Päs, IOP, Bristol, Philadelphia, in press
5. Heidelberg-Moscow collaboration, M. Günther et al., Phys.Rev. D55 (1997) 54; and L. Baudis et al., Phys. Lett. B 407, 219 (1997)