Escalante, G. et al. 2013. Nitrogen fixation in shade trees (Erythrina poeppigiana) in cacao plantations in north Venezuela. Pesquisa Agropecuaria Brasileira. 19, 13 (Jul. 2013), 223–230. DOI:https://doi.org/10.1590/S1678-3921.pab1984.v19.17535.