@article{dick_mangrich_menezes_pereira_2002,  title={Chemical and Spectroscopical Characterization of Humic Acids from two South Brazilian Coals of Different Ranks},  volume={13},  ISSN={0103-5053},  url={https://doi.org/10.1590/S0103-50532002000200008},  DOI={10.1590/S0103-50532002000200008},  number={2},  journal={Journal of the Brazilian Chemical Society},  publisher={Sociedade Brasileira de Química},  author={Dick, Deborah P. and Mangrich, Antonio S. and Menezes, Sonia M. C. and Pereira, Betania F.},  year={2002},  pages={177–182} }