Utomo, B., and R. D. Putri. “The Influence of Project-Based Learning (PJBL) Model on Spatial Thinking Ability in Class SMA PGRI 2 Palembang”. Jurnal Spatial Wahana Komunikasi Dan Informasi Geografi, Vol. 19, no. 1, Oct. 2019, pp. 42 -46, doi:10.21009/spatial.191.06.