Sumarti, Titik, Rokhani Rokhani, and Sriwulan Ferindian Falatehan. “Strategi Pemberdayaan Petani Muda Kopi Wirausaha Di Kabupaten Simalungun”. Jurnal Penyuluhan 13, no. 1 (March 30, 2017): 31-39. Accessed October 3, 2022. https://jma.journal.ipb.ac.id/index.php/jupe/article/view/15165.