Richard W. Pogge. «Real-World Relativity: The GPS Navigation System». Ohio State University. Besøkt 5. oktober 2017. «If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day! The whole system would be utterly worthless for navigation in a very short time.»
