@conference {19814,
	title = {Conceptualising function as covariation through the use of a digital system integrating CAS and Dynamic Geometry},
	booktitle = {Proceedings of the 40th Conference of the International Group for the Psychology of Mathematics Education (PME 40)},
	volume = {3},
	year = {2016},
	pages = {67-74},
	publisher = {PME},
	organization = {PME},
	address = {Szeged, Hungary},
	author = {G-I Kafetzopoulos and G Psycharis},
	editor = {C Cs{\'\i}kos and A Rausch and J Szit{\'a}nyi}
}
