Sae Wai, J., K. Sridith, and O. Thaithong. “Hoya Imperialis Lindl. (Apocynaceae: Asclepiadaceae), a New Record for Thailand”. Thai Forest Bulletin (Botany), no. 36, Dec. 2014, pp. 81-85, https://li01.tci-thaijo.org/index.php/ThaiForestBulletin/article/view/24184.