HadiR. M. P., SutiktoT. and BowoC. (2019) “Soil Productivity Index Based on Soil Taxonomy and Its Correlation with Coffee Productivity in Several Soil Orders: Indeks Produktivitas Tanah Berbasis Soil Taxonomy dan Korelasinya Dengan Produktivitas Kopi pada Beberapa Ordo Tanah”, Jurnal Ilmu Tanah dan Lingkungan, 21(1), pp. 7-12. doi: 10.29244/jitl.21.1.7-12.