Performance evaluation of a portable laser-induced fluorescence spectroscopy system for the assessment of the humification degree of the soil organic matter - Santos, Cleber H; Romano, Renan A; Nicolodelli, Gustavo; Carvalho, Camila M; Villas Boas, Paulino Ribeiro; Martin-Neto, Ladislau; Montes, Celia Regina; Melfi, Adolpho José; Milori, Debora Marcondes Bastos Pereira (Journal of the Brazilian Chemical Society, 2015)