Bonafede, A., Intema, H. T., Brüggen, M., Russell, H. R., Ogrean, G., Basu, K., Sommer, M., van Weeren, R. J., Cassano, R., Fabian, A. C., and Röttgering, H. J. A. 2014. "A giant radio halo in the cool core cluster CL1821+643." Monthly Notices of the Royal Astronomical Society, 444 L44–L48. https://doi.org/10.1093/mnrasl/slu110.