@article{santos_vasconcelos_1999,  title={Obtention of nanostructured silica glass by sol-gel process with incorporation of lead compounds},  volume={2},  ISSN={1516-1439},  url={https://doi.org/10.1590/S1516-14391999000300015},  DOI={10.1590/S1516-14391999000300015},  number={3},  journal={Materials Research},  publisher={ABM, ABC, ABPol},  author={Santos, Ana Maria M. and Vasconcelos, Wander L.},  year={1999},  month={Jul},  pages={201–204} }