1. McKennel, R., in Instrument Manual, third ed., section XI (United Trade Press, London, 1960).
2. Highgate, D. J., thesis, Univ. London (1966).
3. Jobling, A., and Roberts, J. E., in Rheology, Theory and Applications, edit. by Eirich, F. R., 2 (Academic Press, New York, 1958).