1. Hein, G., GNSS Interoperability: Archiving of Global System of Systems or “Does everything Have to be the Same”, Inside GNSS, Jan/Feb 2006, pp. 57–60.
2. Navstar GPS Space Segment/Navigation User Interfaces, IS-GPS-200D, on-line at http://www.navcen.uscg.gov/gps/modernization/IS-GPS-200D-w-IRN -1-7Mar06%20NS.pdf .
3. GPS L1 Civil Signal Modernization (L1C), on-line at http://www.navcen.uscg.gov/gps/modernization/L1/L1Creport-long.pdf .
4. Navstar GPS Space Segment/User Segment L1C Interfaces, Draft IS-GPS-800, 19 April 2006, on-line at http://www.navcen.uscg.gov/gps/modernization/L1/ISGPS-800-19-DRAFT-Apr06.pdf .
5. Navstar GPS Space Segment/User Segment L5 Interfaces, IS-GPS-705, on-line at http://www.navcen.uscg.gov/gps/modernization/Number.pdf .