@unpublished{TUW-120838, author = {Todorova, Sonya and Schuh, Harald}, title = {Global Ionosphere Maps obtained from Global Navigation Satellite System (GNSS) data and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}, year = {2007}, note = {talk: International Scientific ConferenceSGEM 2007, Albena, Bulgarien; 2007-06-10 -- 2007-06-15} }