Djarawula, Elga Farianti, Nugroho Aji Prasetiyo, and Zuni Mitasari. 2022. “The Effect of Combination of Cooperative Learning Type STAD With NHT on Problem Solving Ability in Class X Students at High School”. Journal of Biology Learning 4 (2):84-93. https://doi.org/10.32585/jbl.v4i2.2375.