@unpublished{TUW-120840, author = {Todorova, Sonya and Weber, Robert and Schuh, Harald}, title = {Estimation of GNSS instrumental biasesand satellite altimetry time delays when determining global ionosphere maps}, year = {2007}, note = {poster presentation: EGU 2007, Wien; 2007-04-15 -- 2007-04-20} }