Heikkinen, H., P. Hästö, V. Kangas, and M. Leinonen. “Promoting Exploratory Teaching in Mathematics: A Design Experiment on a CPD Course for Teachers”. LUMAT: International Journal on Math, Science and Technology Education, vol. 3, no. 6, Oct. 2015, pp. 905-24, doi:10.31129/lumat.v3i6.1007.