Thitimetharoch, T., and A. Thammathaworn. “Leaf Anatomy of Coa (Erythroxylum coca Lam,: Erythroxylaceae in Khon Kaen University)(Thai)”. Asia-Pacific Journal of Science and Technology, vol. 12, no. 4, Apr. 2017, pp. 381-6, https://so01.tci-thaijo.org/index.php/APST/article/view/83899.