1. V. A. Syrovoi, ?Invariant-group solutions of the equations of a plane stationary beam of charged particles,? PMTF, no. 4, 1962.
2. V. A. Syrovoi, ?Invariant-group solutions of the equations of a three-dimensional stationary beam of charged particles,? PMTF, no. 3, 1963.
3. D. Gabor, ?Dynamics of electron beams,? Proc. l IRE, vol. 33, no. 11, 1956.
4. H. F. Ivey, ?Cathode field in diodes under partial space-charge conditions,? Phys. Rev., vol. 16, no. 4, 1949.
5. S. Ya. Braude, ?Motion of an electron in electric and magnetic fields allowing for space charge, ? Zh. eksperim. i teor. fiz., vol. 5, no. 7, 1935.