1. Kok, J. A. and M. M. G. Corbey, Appl. Sci. Res.B 4 (1955) 474;B 6 (1957) 197;B 6 (1957) 285.
2. Vogel, J. G., Thesis Utrecht 1938; Kruyt, H. R. and J. G. Vogel, Kolloidzschr.95(1941) 2; Stauff, J., Kolloidzschr.143 (1955) 162.
3. Muth, E., Kolloidzschr.41 (1927) 97. See also Vogel2).
4. Brintzinger, H., R. Haug, und G. Sachs. Farbe und Lack58 (1952) 5, 143, 522;59 (1953) 407;60 (1954) 15, 59, 95. Contains a number of useful references and information.
5. Watson, P. K. and J. B. Higham, Symposium on insulating materials, Proc. Instn. elect. Engrs., vol.100 IIA nr 3 (1953) 111.