1. Bingel, W.A. (1969): Theory of Molecular Spectra (Wiley, New York)
2. Flygare, W.H. (1978): Molecular Structure and Dynamics (Prentice-Hall, New York)
3. Hellwege, K.H. (1974): Einführung in die Physik der Molekülen, Heidelberger Taschenbücher, Bd. 146 (Springer Verlag, Berlin)
4. Gordy, W., Cook, R.L. (1970): Microwave Molecular Spectra 2nd ed. (Wiley, New York)
5. Herzberg, L., Herzberg, G. (1960): “Molecular Spectra”, in Fundamental Formulas of Physics, Menzel, D.H. ed. (Dover, New York) p. 465