โสมภีร์ ปิยะมาศ, and คำวงศ์ วิรุฬห์. “Appropriate Harvesting Stage of Long Pepper (Piper retrofractum Vahl) to achieve Thai Herbal Phamacopeia”. Thai Agricultural Research Journal 33, no. 2 (February 3, 2023): 132–143. accessed September 30, 2026. https://li01.tci-thaijo.org/index.php/thaiagriculturalresearch/article/view/77741.