1. Schnabel, P., Phillips Res. Rep., 1964, vol. 19, p. 43.
2. Schnabel, P., Zt. Ang. Phys., 1967, vol. 22, no. 2, p. 136.
3. Tikhonov, A.N. and Samarskii, A.A., Uravneniya matematicheskoi fiziki (Equations of Mathematical Physics), 7th ed., Moscow: Mos. Gos. Univ., 1999.
4. Pavlov, L.P., Metody izmereniya parametrov poluprovodnikovykh materialov (Methods for Measuring Parameters of Semiconductor Materials), Moscow: Vysshaya Shkola, 1987.
5. Hansen, E.B., Appl. Sci. Res., Sec. B, 1960, vol. 8, p. 93.