Siskawati, F. S. “An Error Analysis of Students With Differences in Learning Outcomes in Solving Story Problems Based on the Newman Procedure”. Jurnal Axioma : Jurnal Matematika Dan Pembelajaran, vol. 2, no. 1, Jan. 2017, pp. 25-36, https://ejurnal.uij.ac.id/index.php/AXI/article/view/284.