TY - CONF AU - Akman, Perihan AU - Fechner, Sabine ED - Finlayson, Odilla ED - McLoughlin, E. ED - Erduran, Sibel ED - Roser, Pinto ID - 23775 T2 - Electronic Proceedings of the ESERA 2017 Conference. Research, Practice and Collaboration in Science Education, Part 1 (co-ed. Finlayson, O. & Roser, P.) TI - Concrete and abstract external respresentations in chemistry education ER -