LEERATIWONG, C., P. CHANTARANOTHAI, and A. J. PATON. “A Synopsis of the Genus Premna L. (Lamiaceae) in Thailand”. Tropical Natural History, vol. 9, no. 2, Oct. 2009, pp. 113-42, https://li01.tci-thaijo.org/index.php/tnh/article/view/102948.