Nurkanti, M., and A. Setiani. “The Conceptual Understanding of Prospective Teachers of Economic Education on Basic Natural Science Through Project-Based Learning Approach”. Proceeding Interuniversity Forum for Strengthening Academic Competency, Vol. 1, no. 1, May 2019, pp. 210 -15, https://proceedings.conference.unpas.ac.id/index.php/ifsac/article/view/159.