Meilon, B., S. Mariani, and I. Isnarto. “Analysis of Mathematical Representation Skills Based on Student Learning Activities in Hands on Activity Assisted Pbl Learning Model”. Unnes Journal of Mathematics Education Research, Vol. 8, no. 2, Jan. 2019, pp. 213-9, https://journal.unnes.ac.id/sju/ujmer/article/view/27777.