1. M. D. Hadley, J. B. McBride, T. W. Edgar, et al., PNNL-17116 1–54 (Pacific Northwest National Laboratory, 2007).
2. P. V. S. Rama Rao, S. Krishna, and J. Vara Prasad, Ann. Geophys. 27, 2101 (2009).
3. E. L. Afraimovich and N. P. Perevalova, GPS Monitoring of the Earth’s Upper Atmosphere (GU NTs RBKh VSNTs SO RAMN, Irkutsk, 2006) [in Russian].
4. B. M. Ledvina, J. J. Makela, and P. M. Kintner, Geophys. Rev. Lett. 29, 1659 (2002).
5. E. L. Afraimovich, V. V. Demyanov, and T. N. Kondakova, GPS Solut. 7, 109 (2003).