1. P.W. Hawkes, E. Kasper, in: Principles of Electron Optics, vol. 2, Academic Press, New York, 1996, Ch. 41.
2. �ber einige Fehler von Elektronenlinsen
3. J.H.M. Deltrap, Ph.D. Thesis, University of Cambridge, 1964.
4. J.H.M. Deltrap, Proceedings third EUREM Congress, Prague, vol. 1, 1964, p. 45.