@article{nielsen_navarra_bracco_2007,  title={Investigating the tetraquark structure of the new mesons},  volume={37},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97332007000100018},  DOI={10.1590/S0103-97332007000100018},  number={1a},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={Nielsen, M. and Navarra, F. S. and Bracco, M. E.},  year={2007},  month={Mar},  pages={56–58} }