@article{raviolo_barbosa_neumann_2009,  title={Characteristics, distribution and diagenetic stages of chert in the La Silla Formation (Lower Ordovician), Argentine Precordillera},  volume={81},  ISSN={0001-3765},  url={https://doi.org/10.1590/S0001-37652009000400015},  DOI={10.1590/S0001-37652009000400015},  number={4},  journal={Anais da Academia Brasileira de Ciências},  publisher={Academia Brasileira de Ciências},  author={Raviolo, Mariana M. and Barbosa, José A. and Neumann, Virgínio H.},  year={2009},  month={Dec},  pages={781–792} }