Agazie, G., Anumarlapudi, A., Archibald, A. M., Arzoumanian, Z., Baier, J., Baker, P. T., …The NANOGrav Collaboration. (2024). The NANOGrav 15 yr Data Set: Search for Transverse Polarization Modes in the Gravitational-wave Background. Astrophysical journal. Letters, 964(1), L14. https://doi.org/10.3847/2041-8213/ad2a51