1. Sizes of papers and boards (British Standard 4000, 1968).
2. Spike, J. E., Amer. J. Phys., 8, 123 (1940).
3. Crommelin, A. C. D., Rep. Progr. Phys. (GB), 5, 92 (1938).
4. Hatch, F. H., and Rastall, R. H., Petrology and the Sedimentary Rocks (London: Thomas Murphy 4th Edn 1965). Pettijohn, E. J., Sedimentary Rocks (London: Harper and Row 2nd edn, 1957).
5. Kaye, G. W. C., and Laby, T. H., Tables of Physical and Chemical Constants, p. 7 ( London: Longmans, 1956 ).