Ramalho, Mauro, and Jaqueline Figuerêdo Rosa. 2010. “Ecological Interaction Between the Tiny Keel Flowers of Stylosanthes Viscosa Sw. (Faboideae) and the Large Bee Xylocopa (Neoxylocopa) Cearensis Ducke, 1910 (Apoidea, Hymenoptera), in Tropical Sand Dune”. Biota Neotropica 10 (3). Sao Paulo, Brazil. //www.biotaneotropica.org.br/BN/article/view/638.