Izwar lubis, Selamat Triono , Ambiyar. “VALIDITY OF PRODUCT ON THE DEVELOPMENT OF COMPASS, OBSERVATION, DEMONSTRATION, EVALUATION (CODE) TRAINING MODEL ”. Turkish Journal of Computer and Mathematics Education (TURCOMAT), vol. 12, no. 12, Aug. 2021, pp. 4753-6, doi:10.17762/turcomat.v12i12.10722.