1. J.D. Mackenzie, in: Modern Aspects in the Vitreous State, vol. 3, Butterworth, London, 1964
2. Conduction in glasses containing transition metal ions
3. D. Adler, in: Amorphous Semiconductors, CRC, Cleveland, OH, 1971
4. I.G. Austine, E.J. Garbett, in: P.G. LeComber, J. Mart (Eds.), Electronic and Structural Properties of Amorphous Semiconductors, Academic Press, London, 1973
5. Electrical properties of semiconducting oxide glasses