Science
- Bureau des longitudes
- http://www.bdl.fr
- Service Hydrographique et Océanographique de la Marine
- http://www.shom.fr/
- United Kingdom Hydrographic Office
- http://www.ukho.gov.uk/
- Her Majesty's Nautical Almanac Office
- http://www.nao.rl.ac.uk/
- U.S. Naval Observatory
- http://aa.usno.navy.mil/
- National Oceanic and Atmospheric Administration
- http://www.noaa.gov/charts.html
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