A. V. Astin & H. Arnold Karo, (1959), Refinement of values for the yard and the pound, Washington DC: National Bureau of Standards, republished on National Geodetic Survey website and the Federal Register (Doc. 59-5442, Filed, 30 June 1959, 8:45 a.m.). Gearchiveerd op 17 november 2024.
A. V. Astin & H. Arnold Karo, (1959), Refinement of values for the yard and the pound, Washington DC: National Bureau of Standards, republished on National Geodetic Survey website and the Federal Register (Doc. 59-5442, Filed, 30 June 1959, 8:45 a.m.). Gearchiveerd op 17 november 2024.