SARTIKA, D.; SIHOMBING, A. F. .; HASIBUAN, R. Y. .; SIAHAAN , P. . G. .; PA, R. B. B. Development of geographical indication based Sipirok coffee marketing strategy to improve farmers’ welfare. Jurnal Mantik, [S. l.], v. 7, n. 3, p. 2686-2692, 2023. Disponível em: https://iocscience.org/ejournal/index.php/mantik/article/view/4281. Acesso em: 10 may. 2026.