@conference{b5c67325a53e47f7a6bbb0f085afe743,
title = "Designing instruction on proportional reasoning with average speed",
keywords = "Wiskunde en Informatica (WIIN), Mathematics, Pedagogie en Andragogie/Onderwijskunde (PEAN), Landbouwwetenschappen, Natuurwetenschappen, Wiskunde: algemeen",
author = "K.P.E. Gravemeijer and {van Galen}, F.H.J. and R. Keijzer",
year = "2005",
month = jul,
day = "10",
language = "Undefined/Unknown",
pages = "103--108",
note = "Unknown event ; Conference date: 01-01-1950 Through 14-08-2013",
}