@article{paião_pereira_watanabe_2001,  title={Soda-lime glass with gradient of refraction index (GRIN)},  volume={31},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97332001000100014},  DOI={10.1590/S0103-97332001000100014},  number={1},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={Paião, J. R. B. and Pereira, F. and Watanabe, S.},  year={2001},  month={Mar},  pages={77–79} }