Silveira, Pedro Marques da, and Augusto Cesar de Oliveira Gonzaga. “Portable Chlorophyll Meter Can Estimate the Nitrogen Sufficiency Index and Levels of Topdressing Nitrogen in Common Bean”. Pesquisa Agropecuária Tropical [Agricultural Research in the Tropics], vol. 47, no. 1, Jan. 2017, pp. 1-6, https://doi.org/10.5216/pat.v47i1.42128.