@article{amato_2002,  title={Light Absorption near Threshold with Phonon Participation for Impurities in Semiconductors},  volume={24},  ISSN={1806-1117},  url={https://doi.org/10.1590/S1806-11172002000400003},  DOI={10.1590/S1806-11172002000400003},  number={4},  journal={Revista Brasileira de Ensino de Física},  publisher={Sociedade Brasileira de Física - SBF},  author={Amato, M. A.},  year={2002},  pages={379–382} }