1. On position definition of ships at sea by means of radiotechnical methods;Schegolev;Proc. Acad. Sci. USSR.,1940
2. 21 O'brien W. J. and the Decca Record Co. Ltd. British Patent Provisional Specification No. 620, 479 (final acceptance 1949).
3. Gee: a radio navigational aid;Dippy;J.I.E.E.,1946