1. 8 Bowditch N. (1977). American Practical Navigator (chapter XXI). US Defence Mapping Agency.
2. Astro without azimuth;Brown;Journal,1991
3. Astronomical fixes without an assumed position;Spencer;Journal,1990
4. Computation of an astronomical running fix;Williams;Journal,1990
5. A mathematical method of obtaining an astronomical vessel position;Chiesa;Journal,1990