@article{fernandes_giacomelli_giovanela_vaz_szpoganicz_sierra_2009,  title={Potentiometric acidity determination in humic substances influenced by different analytical procedures},  volume={20},  ISSN={0103-5053},  url={https://doi.org/10.1590/S0103-50532009000900021},  DOI={10.1590/S0103-50532009000900021},  number={9},  journal={Journal of the Brazilian Chemical Society},  publisher={Sociedade Brasileira de Química},  author={Fernandes, Andreia N. and Giacomelli, Cristiano and Giovanela, Marcelo and Vaz, Denise O. and Szpoganicz, Bruno and Sierra, Maria M. D.},  year={2009},  pages={1715–1723} }