@conference {LadKor-EMWMAA-2012,
	title = {Early maths with multi-touch {\textendash} an activity-theoretic approach},
	booktitle = {Proceedings of POEM 2012},
	year = {2012},
	keywords = {invited},
	url = {http://cermat.org/poem2012/main/proceedings_files/Ladel-Kortenkamp-POEM2012.pdf},
	author = {Ladel, Silke and Kortenkamp, Ulrich}
}
