1. KOHLER, A., Z. Wiss. Microskopie, 1904, 21, 129, 275.
2. FREED, J. J., in: Physical Techniques in Biological Research, 2nd Edn, vol. IIIc, A. W. Pollister, Ed., 1969, Academic Press, New York.
3. BLOUT, E. R., in: Advances in Biological and Medical Physics, vol. III, J. H. Lawrence and C. A. Tobias, Eds., 1953, Academic Press, New York.
4. Zworykin, V. K. and Hatke, F. L., Science, 1957, 126, 805.
5. WITTE, S., Blut, 1968, 8, 81.