S. A. de Lima Filho and A. M. L. Neptune, “ Effects of nitric and ammonium fertilizers on the transport of NO-3 and NH+4 in a field grown with Vigna unguiculata (L.) Walp ”, An. Esc. Super. Agr. Luiz de Queiroz, vol. 39, no. 2, pp. 1047–1087, Jan. 1982, doi: 10.1590/S0071-12761982000200024.