@inproceedings{sgem2005paper,
  title = {USING GPS FOR DETERMINATION OF THE IONOSPHERE},
  author = {S. Todorova and T. Hobiger and R. Weber and H. Schuh},
  booktitle = {5th International Scientific Conference - SGEM2005},
  year = {2005},
  pages = {605-614},
  publisher = {SGEM Scientific GeoConference},
  doi = {}
}