Gultom, Saurmaida. 2017. “The Effect of Problem Based Learning Strategic and Divergent Thinking Style on The Ability to Solve Environmental The Problems (an Experimental Study at SMP Negeri 161 Jakarta, 2015)”. IJEEM - Indonesian Journal of Environmental Education and Management 1 (2), 66 - 82. https://journal.unj.ac.id/unj/index.php/ijeem/article/view/3701.