@conference {754, title = {Finger-symbol-sets and multi-touch for a better understanding of numbers and operations}, booktitle = {Proceedings of the Seventh Congress of the European Society for Research in Mathematics Education.}, year = {2011}, month = {Februar}, publisher = {Congress of the European Society for Research in Mathematics Education (CERME)}, organization = {Congress of the European Society for Research in Mathematics Education (CERME)}, address = {Rzesz{\'o}w, Poland}, author = {Ladel, Silke and Kortenkamp, Ulrich}, editor = {Pytlak, Marta and Rowland, Tim and Swoboda, Ewa} } @conference {753, title = {Implementation of a multi-touch-environment supporting finger-symbol-sets}, booktitle = {Proceedings of the Seventh Congress of the European Society for Research in Mathematics Education.}, year = {2011}, month = {Februar}, publisher = {Congress of the European Society for Research in Mathematics Education (CERME)}, organization = {Congress of the European Society for Research in Mathematics Education (CERME)}, address = {Rzesz{\'o}w, Poland}, author = {Ladel, Silke and Kortenkamp, Ulrich}, editor = {Pytlak, Marta and Rowland, Tim and Swoboda, Ewa} }