@conference {761,
	title = {Designing a technology based learning environment for place value using artefact-centric Activity Theory. Research Forum Activity Theoretical approaches to mathematics classroom practices with the use of technology},
	booktitle = {Proceedings of the 37th Conference of the International Group for the Psychology of Mathematics Education},
	year = {2013},
	publisher = {Psychology of Mathematics Education (PME)},
	organization = {Psychology of Mathematics Education (PME)},
	address = {Kiel, Germany},
	author = {Kortenkamp, Ulrich and Ladel, Silke},
	editor = {Lindmeier, Anke M. and Heinze, Aiso}
}
@inbook {747,
	title = {Arbeitsgruppe "Neue Technologien im Mathematikunterricht der Grundschule" - neu: "Lernen, Lehren und Forschen mit Neuen Medien im Mathematikunterricht der Primarstufe"},
	booktitle = {Beitr{\"a}ge zum Mathematikunterricht 2010 - Beitr{\"a}ge zur 44. Jahrestagung der Gesellschaft f{\"u}r Didaktik der Mathematik vom 08.03 bis 12.03.2010 in M{\"u}nchen},
	year = {2010},
	pages = {961-964},
	publisher = {WTM-Verlag},
	organization = {WTM-Verlag},
	address = {M{\"u}nster},
	author = {Ladel, Silke and Schreiber, Christof},
	editor = {Lindmeier, Anke M. and Ufer, Stefan}
}
