1. Metrology and the State: Science, Revenue, and Commerce
2. The International System of Units (SI) 1998
3. The International System of Units (SI) Supplement 2000: Addenda and Corrigenda to the 7th edition (1998) 2000
4. J. C. Maxwell, Address to the Mathematical and Physical Sections of the British Association, Liverpool, September 15, 1870 (from the British Association Report, Vol. XL), reproduced in The Scientific Papers of James Clerk Maxwell, W. D. Niven, Ed., Vol. 2 (Cambridge Univ. Press, Cambridge, 1890), p. 225.
5. Testing the Stability of Fundamental Constants with theHg+199Single-Ion Optical Clock