Coronal activity cycles in 61 Cygni A. Hempelmann, J. Robrade, J. H. M. M. Schmitt, F. Favata, S. L. Baliunas and J. C. Hall A&A, 460 1 (2006) 261-267 Published online: 12 September 2006 DOI: 10.1051/0004-6361:20065459