Trieni, Pultion. “The Difficulties of Students in Learning Mathematics by Using Development Learning Sequences Approach in Sd Negeri No. 08 Koto Barapak Kecamatan Bayang”. Jurnal Ilmiah Pendidikan Scholastic, vol. 2, no. 1, Mar. 2018, pp. 39-49, doi:10.36057/jips.v2i1.307.