Simamora, Jupri, et al. “DETERMINATION TYPE OF ALLOPHANE ON ANDISOL IN DOLAT RAKYAT VILLAGE TIGA PANAH DISTRICT, REGENCY OF KARO”. Jurnal Online Pertanian Tropik, vol. 2, no. 3, Dec. 2015, pp. 228-3, doi:10.32734/jopt.v2i3.2916.