Laura Butarbutar, Yenny, and Nurmely Violita Sitorus. “ANALISIS TATA NIAGA BIJI KOPI ROBUSTA DI KABUPATEN DAIRI”. Akrab Juara : Jurnal Ilmu-ilmu Sosial 4, no. 1 (February 5, 2019): 176–190. Accessed January 28, 2026. https://www.akrabjuara.com/index.php/akrabjuara/article/view/449.