S. Tampubolon, F. A. S. Sihaloho, and V. U. Hasibuan, “IMPROVING STUDENT LEARNING OUTCOMES IN MATHEMATICS SUBJECTS USING PROBLEM SOLVING METHODS IN CLASS IV SD 107400 B. KHALIPAH ACADEMIC YEAR 2020-2021”, REKOGNISI, vol. 7, no. 2, pp. 28–34, Dec. 2022.