@article{couto_2013,  title={Green's functions for the wave, Helmholtz and Poisson equations in a two-dimensional boundless domain},  volume={35},  ISSN={1806-1117},  url={https://doi.org/10.1590/S1806-11172013000100004},  DOI={10.1590/S1806-11172013000100004},  number={1},  journal={Revista Brasileira de Ensino de Física},  publisher={Sociedade Brasileira de Física - SBF},  author={Couto, Roberto Toscano},  year={2013},  month={Jan},  pages={01–08} }