A. M. P. Baltazar and I. E. Buot, Jr., “Resolving Taxonomic Confusion between Hoya cumingiana Decne. and Hoya densifolia Turcz. (Apocynaceae) using Leaf Architectural Analysis”, Thai. Nat. Hist. Mus. J., vol. 13, no. 2, pp. 77–89, Dec. 2019.