Darmadi Erwin Harahap, Eka Nurwani Ritonga, Qorry Hilmiyah Harahap, Msy.Nurhalimah, Muhammad Darwis, and Dodi Syahrin, “Patchouli Oil Quality In Various Methods of Drying Plant Materials Nilam (Pogostemon cablin Benth)”, IJSE, vol. 6, no. 2, pp. 916–920, Jun. 2026.