On the long-term correlation between the flux in the Ca ii H & K and Hα lines for FGK stars J. Gomes da Silva, N. C. Santos, I. Boisse, X. Dumusque and C. Lovis A&A, 566 (2014) A66 Published online: 17 June 2014 DOI: 10.1051/0004-6361/201322697