@article{silveira_gonzaga_2017,  title={Portable chlorophyll meter can estimate the nitrogen sufficiency index and levels of topdressing nitrogen in common bean},  volume={47},  ISSN={1983-4063},  url={https://doi.org/10.1590/1983-40632016v4742128},  DOI={10.1590/1983-40632016v4742128},  number={1},  journal={Pesquisa Agropecuária Tropical},  publisher={Escola de Agronomia/UFG},  author={Silveira, Pedro Marques da and Gonzaga, Augusto Cesar de Oliveira},  year={2017},  month={Jan},  pages={1–6} }