Ningsih Sagala, P. , Suhendro L, P. and Widyastuti, E. 2022. Development Of First High School Mathematics LKPD Based On Case Method Integrated Local Culture Mandailing Tribe. International Journal of Educational Research & Social Sciences . 3, 4 (Sep. 2022), 1734–1743. DOI:https://doi.org/10.51601/ijersc.v3i4.463.