Slamet, Bejo, et al. “Impact of Land Cover Changes in Tropical Lowland Rainforest Transformation System to Soil Properties”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 22, no. 2, May 2015, pp. 316-28, https://gssrr.org/JournalOfBasicAndApplied/article/view/4000.