@inproceedings{sgem2006paper,
  title = {COMBINATION OF GPS AND SATELLITE ALTIMETRY DATA FOR GLOBAL IONOSPHERE MAPS},
  author = {S. Todorova and T. Hobiger and H. Schuh},
  booktitle = {6th International Scientific Conference - SGEM},
  year = {2006},
  pages = {265-278},
  publisher = {SGEM Scientific GeoConference},
  doi = {}
}