1. M. Born, Ann. Physik., 55:177–240 (1918).
2. R. Jernigan, chapter in this volume.
3. P. Debye, and E. Marx (eds.), “Handbuch der Radiologie,” Vol. 6, Leipzig (1925), pp. 597–790.
4. P. Debye, and H. Sack, in: E. Marx (ed.), “Handbuch der Radiologie,” Vol. 6, Leipzig (1934).
5. J. R. Partington, “An Advanced Treatise on Physical Chemistry,” Vol. 4, Physico-Chemical Optics, Longmans, Green and Co. Ltd., London and Toronto (1953), p. 280.