Puspita sari, Niken, Teguh Iman Santoso, and Surip Mawardi. “Distribution of Soil Fertility of Smallholding Arabica Coffee Farms at Ijen-Raung Highland Areas Based on Altitude and Shade Trees”. Pelita Perkebunan (a Coffee and Cocoa Research Journal) 29, no. 2 (August 31, 2013). Accessed July 17, 2024. https://ccrjournal.com/index.php/ccrj/article/view/57.