@article{brinkmann_santos_1973,  title={Natural Waters in Amazonia. VI-Soluble Calcium Properties (},  volume={3},  ISSN={0044-5967},  url={https://doi.org/10.1590/1809-43921973032033},  DOI={10.1590/1809-43921973032033},  number={2},  journal={Acta Amazonica},  publisher={Instituto Nacional de Pesquisas da Amazônia},  author={Brinkmann, W. L. F. and Santos, A. dos},  year={1973},  month={Aug},  pages={33–40} }