Ural, Evrim, and Guzide Dadli. “The Effect of Problem-Based Learning on 7th-Grade Students’ Environmental Knowledge, Attitudes, and Reflective Thinking Skills in Environmental Education”. Journal of Education in Science, Environment and Health, vol. 6, no. 3, Apr. 2020, pp. 177-92, https://www.jeseh.net/index.php/jeseh/article/view/283.