G. B. Ferreira, R. L. F. Fontes, V. H. A. Venegas, M. P. F. Fontes, and J. M. N. Pereira, “Interference of iron on soil boron determination with azomethine-H in acid solutions”, PAB, vol. 37, no. 9, pp. 1311–1318, Sep. 2002, doi: 10.1590/S1678-3921.pab2002.v37.6471.