@unpublished{TUW-121207, author = {Alizadeh, Mahdi and Todorova, Sonya and Kudryashova, Maria and Weber, Robert and Schuh, Harald}, title = {Assessment of GNSS and Satellite Altimetry Combined Global Ionospheric Maps Using Precise Point Positioning}, year = {2008}, note = {talk: Egu 2008, Vienna; 2008-04-14 -- 2008-04-19} }