Widiastuti, W., U. Rajamudin, and I. Isrun. “Studi Kualitas Tanah Pada Toposequen Sub Das Poboya, Kota Palu”. AGROTEKBIS : JURNAL ILMU PERTANIAN (e-Journal), Vol. 4, no. 5, Oct. 2016, pp. 544-52, http://103.245.72.23/index.php/agrotekbis/article/view/57.