@article{vasconcelos_1998,  title={Connectivity in sol-gel silica glasses},  volume={21},  ISSN={0100-4042},  url={https://doi.org/10.1590/S0100-40421998000400026},  DOI={10.1590/S0100-40421998000400026},  number={4},  journal={Química Nova},  publisher={Sociedade Brasileira de Química},  author={Vasconcelos, Wander L.},  year={1998},  month={Jul},  pages={514–516} }