Rosa, Hugo José Andrade, et al. “Sugarcane Response to Nitrogen Rates, Measured by a Canopy Reflectance Sensor”. Pesquisa Agropecuaria Brasileira, vol. 50, no. 9, Oct. 2015, pp. 840-8, doi:10.1590/S1678-3921.pab2015.v50.21093.