@conference {LadKor-AAMTEML-2011,
	title = {An activity-theoretic approach to multi-touch tools in early maths learning},
	booktitle = {Proceedings of ATATEMLO 2011 in Paris},
	year = {2011},
	keywords = {refereed},
	author = {Ladel, Silke and Kortenkamp, Ulrich}
}
