Nasrul, Besri, and . Idwar. “Digital Analyses of Landsat ETM+ for Identify Agroforestry System in Riau”. JOURNAL OF TROPICAL SOILS 14, no. 1 (January 1, 2009): 81–87. Accessed July 14, 2025. https://journal.unila.ac.id/index.php/tropicalsoil/article/view/20.