@article{TUW-120576, author = {Hobiger, Thomas and B{\"o}hm, Johannes and Todorova, Sonya and Schuh, Harald}, title = {The project ''VLBIonos'' - how VLBI contributes to ionospheric research}, journal = {Proceedings of the 16th Working Meeting on European VLBI for Geodesy and Astronomy}, year = {2003}, volume = {BKG} }