1. K. Rebane, Impurity Spectra of Solids (Plenum, New York, 1970).
2. Yu. E. Perlin and B. S. Tsukerblat, Electron-Vibrational Interaction in Optical Spectra of Impurity Paramagnetic Ions (Shtintsa, Kishinev, 1974) [in Russian].
3. Zero-Phonon Lines and Spectral Hole Burning in Spectroscopy and Photochemistry, Ed. by O. Sild and K. Haller (Springer, Berlin, Heidelberg, 1988).
4. Y. Toyozawa, Optical Processes in Solids (Cambridge Univ. Press, Cambridge, 2003).
5. I. S. Osad’ko, Selective Spectroscopy of Single Molecules (Springer, Berlin, 2003).