1. V.E.Coslett, Introduction to Electron Optics, Clarendon Press, Oxford (1946).
2. P.Grivet, Electron Optics, Pergamon Press, New York and London (1965).
3. A. Septier (Ed.), Focusing of Charged Particles,Academic Press, New York (1967)(two volumes).
4. V.K.Zworykin, G.A.Morton, E.G.Ramberg, J.Hillier, and A.W.Vance, Electron Optics and the Electron Microscope, John Wiley and Sons, New York (1945).
5. V.K.Zworykin et al., Electron Optics and the Electron Microscope,John Wiley and Sons, New York (1945), p. 423.