1. A History of Engineering Drawing P. J. Booker 1963, Pi 5.
2. ibid, 131 7.
3. Encyclopedia Diderot I Art Militaire, 131 IV.
4. How to Identify Old Maps and Globes R. Lister 1965, 55.
5. First Edition of the One Inch Ordnance Survey reprinted by David & Charles, edited J. B. Harley, 1970.