1. Adamiak, K.: Doctor thesis, Technical University of Szczecin 1976 (unpublished)
2. Glaser, W.: Grundlagen der Elektronenoptik. Wien: Springer 1952
3. Grabar, L. L.: Power Electronics, vol. 5 (in Russian). Moscow: Nauka (1968) 195–208
4. Kapica, S. P.: Power Electronics, vol. 5 (in Russian). Moscow: Nauka (1963) 108–118
5. Kelman, W. M.: et al. Zh. Techn. Fiz. 24 (1959) 1219