1. A. H. Wilson, Proc. Roy. Soc. (London), 133A:458 (1931).
2. F. F. Vol’kenshtein, Electrical Conductivity of Semiconductors [in Russian], Gostekhizdat, 1947.
3. A. I. Ansel’m, Introduction to the Theory of Semiconductors [in Russian], Fizmatgiz, 1963.
4. H. Brooks, Collection: Problems in Modern Physics [Russian translation], Vol. 8, p. 74 (1957).
5. R. A. Smith, Semiconductors, Cambridge University Press, 1961.