Lismayuni, L., V. M. Rambitan, and S. V. Lumowa. “THE EFFECTIVENESS OF PROBLEM - BASED LEARNING MODEL LEARNING DEVICES”. IJER - INDONESIAN JOURNAL OF EDUCATIONAL REVIEW, Vol. 7, no. 02, Nov. 2020, pp. 51-55, http://103.8.12.212:33180/unj/index.php/ijer/article/view/23249.