Amin, Zakaria, et al. “Pengaruh Pencampuran Abu Cangkang Kelapa Sawit Terhadap Nilai Kuat Geser Tanah Lempung”. Jurnal Taxiway, vol. 1, no. 1, July 2019, pp. 1-8, https://journal.upp.ac.id/index.php/Jurnaltaxiway/article/view/133.