Sihotang, Jusmer, Nancy Nopeline, Martin Luter Purba, and Yatatema Zai. “Studi Determinan Ekspor Kopi Indonesia Ke Amerika Serikat”. Jurnal Ekuilnomi 6, no. 1 (February 25, 2024): 77–88. Accessed November 22, 2024. https://jurnal.usi.ac.id/index.php/ekuilnomi/article/view/359.