Zus, F., Grunwaldt, L., Heise, S., Michalak, G., Schmidt, T., Wickert, J. (2014): Atmosphere sounding by GPS radio occultation: First results from TanDEM-X and comparison with TerraSAR-X. - Advances in Space Research, 53, 2, 272-279.https://doi.org/10.1016/j.asr.2013.11.013