@inproceedings{TUW-119974, author = {Todorova, Sonya and Hobiger, Thomas and Weber, Robert and Schuh, Harald}, title = {Using GPS for determination of the ionosphere}, booktitle = {Proceedings of the International Scientific Conference SGEM 2005}, year = {2005}, pages = {605--613}, publisher = {SGEM 2005}, address = {Albena, Bulgaria} }