Faria Vieira, M., and G. John Shepherd. “Removal and Insertion of Pollinia in Flowers of <i>Oxypetalum</i≫ (Asclepiadaceae) in Southeastern Brazil”. Revista De Biología Tropical, vol. 50, no. 1, Mar. 2002, pp. 37–43, https://revistas.ucr.ac.cr/index.php/rbt/article/view/16063.