Saito, S.M.T. and Neptune, A.M.L. (1976) “ Effect of organic matter and of a nitrification inhibitor ‘AM’ on the uptake of 15NH4 and 15NO3 by maize ”, Anais da Escola Superior de Agricultura Luiz de Queiroz, 33, pp. 721–750. doi:10.1590/S0071-12761976000100060.