Setiawan, Yayan Eryk Setiawan, and Sunardi. “Classification of Errors in Determining Trigonometry Function Values at Standard Positions”. JRAMathEdu (Journal of Research and Advances in Mathematics Education) 8, no. 2 (April 30, 2023): 123–139. Accessed November 17, 2025. https://journals2.ums.ac.id/jramathedu/article/view/1625.