1. R. L. Greene, D. D. Sell and R. M. White, Proc. Conf. on Optical Properties of Ions in Crystals (to be published).
2. R. E. Dietz, H. J. Guggenheim and A. Misetich, Proc. Conf. on Optical Properties of Ions in Crystals (to be published).
3. R. E. Dietz and A. Misetich, accompanying paper.
4. R. E. Dietz, A. Misetich, H. J. Guggenheim and A. E. Meixner (to be published).
5. The difference in energy between ψg and yψu will be of the order of the dispersion of the intrinsic exciton El from which they were formed. Experiments on the intrinsic exciton side band emission suggest such dispersion is less than 1 cm-1.