1. Pierce, J. R., 1954, Theory and Design of Electron Beams (Van Nostrand).
2. Dryden, V.W., 1962, J A P33, 3118–3124.
3. Harker, K.J., 1960, J A P31, 2165–2170; 1962, J A P33, 1861–1863.
4. Kirstein, P.T., Kino, G.S. and Waters, W.E., 1967, Space Charge Flow (McGraw Hill).
5. Manuilov, V.N. and Tsimring, Sh. E., 1978, R. Eng. El. Phys.23(7), 1486(Russian), 111–119 (English).