@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}
}
