Goldberg, L. “Patterns of Nectar Production and Composition, and Morphology of Floral Nectaries in <i>Helicteres guazumifolia</i> and <i>Helicteres baruensis</i> (Sterculiaceae): Two Sympatric Species from the Costa Rican Tropical Dry Forest”. Revista De Biología Tropical, vol. 57, no. S1, Nov. 2009, pp. 161–177, doi:10.15517/rbt.v57i0.21294.