@article{TUW-120860, author = {Todorova, Sonya and Schuh, Harald}, title = {Global Ionosphere Maps obtained from Global Navigation Satellite System (GNSS) data and their performance after integration of satellite altimetry measurements}, journal = {Proceedings of the International Scientific Conference SGEM}, year = {2007}, volume = {7}, number = {full paper on included CD}, pages = {99} }