* U.S. Army Corps of Engineers manual: and* National Geodetic Survey Orbits for the Global Positioning System satellites in the Global Navigation Satellite System* GPS PPS Performance Standard—The official Precise Positioning Service specification* GPS and GLONASS Simulation (Java applet) Simulation and graphical depiction of space vehicle motion including computation of dilution of precision (DOP)* Navipedia information on GPS—Wiki initiated by the European Space Agency* Relativity Science Calculator - Explaining Global Positioning System
* The GPS Program Office (GPS Wing)—Responsible for designing and acquiring the system on behalf of the United States Government.