1. Kohler, A., Z. Wiss. Microskopie, 21 (1904) 129, 275.
2. Billingham, N. C. & Calvert, P. D., Dev. Polymer Char., 3 (1982) 229.
3. Freed, J. J., in Physical Techniques in Biological Research, 2nd edn, Vol. IIIc, ed. A. W. Pollister, Academic Press, New York, 1969.
4. Curson, A. D., Proc. Roy. Microsc. Soc., 7 (1972) 96.
5. Ornstein, N., J. Mt Sinai Hospital, 6 (1957) 1066.