Sallah, E. K. . ., A. . Owusu, and P. K. . Butakor. “Problem Based Learning: Errors Minimization, Conceptual and Procedural Understanding in Trigonometry”. African Journal of Educational Studies in Mathematics and Sciences, vol. 19, no. 1, Oct. 2023, pp. 1-18, https://journals.uew.edu.gh/index.php/ajesms/article/view/199.