Nguyen, Ngoc-Giang, and Huyen - Trang Pham. 2020. “Constructivist Learning and the Law of Sines in Advanced 10th Grade Geometry Textbooks in Vietnam”. International Journal of Learning, Teaching and Educational Research 19 (1):38-59. http://www.ijlter.myres.net/index.php/ijlter/article/view/490.