@conference {19834,
	title = {Meanings for angle through geometrical constructions in 3d space},
	booktitle = {Proceedings of the 33rd Conference of the International Group for the Psychology of Mathematics Education (PME 33)},
	volume = {3},
	year = {2009},
	pages = {457-464},
	publisher = {PME},
	organization = {PME},
	address = {Thessaloniki, Greece},
	author = {C Kynigos and G Psycharis and M Latsi},
	editor = {M. Tzekaki and M Kaldrimidou and C Sakonidis}
}
