@article{cavalcante_borges_2004,  title={Phase-shift definition for pion-nucleon scattering from chiral perturbation theory},  volume={34},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97332004000200024},  DOI={10.1590/S0103-97332004000200024},  number={1a},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={Cavalcante, Isabela P. and Borges, J. Sá},  year={2004},  month={Mar},  pages={259–262} }