Detection of diffuse radio emission in the galaxy clusters A800, A910, A1550, and CL 1446+26 F. Govoni, C. Ferrari, L. Feretti, V. Vacca, M. Murgia, G. Giovannini, R. Perley and C. Benoist A&A, 545 (2012) A74 Published online: 10 September 2012 DOI: 10.1051/0004-6361/201219151