Hutagaol, K. e.a. 2020. THE ING NGARSA SUNG TULADHA COOPERATIVE LEARNING MODEL AND STUDENTS’ PROBLEM SOLVING ABILITIES. JOHME: Journal of Holistic Mathematics Education. 3, 2 (mei 2020), 118–126. DOI:https://doi.org/10.19166/johme.v3i2.2005.