1. The Statute for Measuring Land, 33 Edward I, Stat. 6, A. D. 1305 (in Latin).
2. Airy, G. B., Phil. Trans. Roy. Soc., 147, 621 (1857).
3. Barrell, H., Proc. Roy. Soc., A, 186, 164 (1946).
4. Report on the Comparisons of the Parliamentary Copies of the Imperial Standards with the Imperial Standard Yard and the Imperial Standard Pound and with each other during the Years 1947 to 1948 (H.M.S.O., London, 1950).
5. Report on the Comparisons of the Parliamentary Copies of the Imperial Standards with each other during the Year 1957 (H.M.S.O., London, 1958).