P. PALEE, J. DENDUANGBORIPANT, V. ANUSARNSUNTHORN, and M. MÖLLER, “MOLECULAR PHYLOGENY AND CHARACTER EVOLUTION OF DIDYMOCARPUS (GESNERIACEAE) IN THAILAND”, Edinburgh J. Bot., vol. 63, no. 2-3, pp. 231–251, Jul. 2006, doi: 10.1017/S0960428606000540.