1. All references to Navigation refer to the Journal of the Institute of Navigation (United States), Suite 832, 815-15th St., N.W., Washington, D.C., 2005.
2. All references to The Journal of Navigation refer to The Institute of Navigation (United Kingdom) at the Royal Geographical Society, Kensington Gore, London SW7.
3. AC-90-45. “Approval of Area Navigation Systems for Use in the U.S. National Airspace”, Federal Aviation Administration, Washington D.C., 18 Sep 69.
4. Ackerman, J.D. “Testing a Modern Gyromagnetic Compass”, The Journal of Navigation, Vol. 18, No. 1, January 1965.
5. “Air Navigation Radio Aids”, Transport Canada issued quarterly, Information Canada.