Almeida, A.M.M. de et al. 2018. Density, characterization and efficiency of Nitrogen fixing bacteria in areas of degraded caatinga. Revista Verde de Agroecologia e Desenvolvimento Sustentável. 13, 1 (Jan. 2018), 16–21. DOI:https://doi.org/10.18378/rvads.v13i1.5282.