1. H. Ebert, Condensed Physics Handbook [Russian translation], Fizmatgiz, Moscow (1963), p. 281.
2. T. Swensson, Lichtelectrische Untersuchungen on Salzlösungen, Mineralogi och Geologi,7, No. 25, 1 (1919).
3. M. Wildermann, Zeitschrift fur Phisikalische Chemie Helf,2, 209 (1905).
4. O.D. Houlson, Course in Physics [Russian translation], Vol. 4 (1925), p. 597.
5. W. Obolensky, Ann.d. Physik, IV Folge,39, 961 (1918).