title = {Interoperable Interactive Geometry For Europe {\textendash} First Technological and Educational Results and Future Challenges of the Intergeo Project},
+
title = {Interoperable Interactive Geometry For Europe {\"u} First Technological and Educational Results and Future Challenges of the Intergeo Project},
−
booktitle = {Proceedings of the Sixth Congress {\textendash} of the European Society for Research in Mathematics Education. January 28th - February 1st 2009, Lyon (France)},
+
booktitle = {Proceedings of the Sixth Congress of the European Society for Research in Mathematics Education. January 28th - February 1st 2009, Lyon (France)},