Barcelos, J. P. Q., E. Furlani Junior, H. P. G. Reis, F. F. Putti, and A. R. dos Reis. “DIAGNOSIS OF NITROGEN AND NICKEL REQUIREMENTS FOR COTTON PLANTS USING A PORTABLE CHLOROPHYLL METER”. Revista Brasileira De Engenharia De Biossistemas, vol. 10, no. 1, Mar. 2016, pp. 97-106, doi:10.18011/bioeng2016v10n1p97-106.