1. A. R. Katritskii (ed.),Physical Methods in Chemistry of Heterocyclic Compounds [in Russian], Moscow (1966).
2. L. M. Sverdlov, M. A. Kovner, and E. P. Krainov,Vibrational Spectra of Polyatomic Molecules [in Russian], Moscow (1970).
3. R. G. Semenova, L. I. Kozhevina, and V. I. Rybachenko,Zh. Prikl. Spektrosk., 56, 222–228 (1992).
4. A. R. Katritzky, C. R. Palmer, F. J. Swinbourne, T. T. Tidwell, and R. D. Topson,J. Am. Chem. Soc.,91, 636–646 (1969).
5. C. Yu. Chotiy, L. I. Kozhevina, V. I. Rybachenko, and E. V. Titov,J. Mol. Struct.,114, 379–384 (1984).