1. GPS navigation algorithms;Axelrad;Global positioning system: theory and applications,1996
2. Spaceborne GPS current status and future visions;Bauer,1998
3. Becker, W., Trumper, J., A&A, 341, 803, 1999.
4. Becker, W., Werner, M., Jessner, A., , 2013 (preprint).
5. Bernhardt, M. G., Prinz, T., Becker, W., Walter, U., In High Time Resolution Astrophysics IV, PoS (HTRA-IV)050 (pp. 1-5), 2010.