1. H.R. Griem, Plasma Spectroscopy (McGraw-Hill Book Company, NY, 1964)
2. G. Herzberg, Molecular Spectra and Molecular Structure, ISBN 0-89464-268-5, Krieger Publishing Company, Malabar, Florida, Second Edition 1950 (Reprint Edition 1989 w/correction)
3. W.L. Wiese, Ch. 6. Line broadening, in Plasma Diagnostic Techniques, ed. by R.H. Huddlestone, S.L. Leonard (Academic Press, New York, 1965)
4. H.W.Y. Drawin, Validity conditions for local thermodynamic equilibrium. Z. Angew. Phys. 228, 99–119 (1969)
5. R.W.P. McWhirter, Ch. 5. Spectral intensities, in Plasma Diagnostic Techniques, ed. by R.H. Huddlestone, S.L. Leonard (Academic Press, New York, 1965), p. 206