Souto, Sebastião M., and Johanna Döbereiner. “Methodology for Measuring N2 Fixation in Detached Roots of Tropical Forage Grasses”. Pesquisa Agropecuaria Brasileira, vol. 19, no. 5, Apr. 2014, pp. 553-65, doi:10.1590/S1678-3921.pab1984.v19.15599.