Exploring the α-enhancement of metal-poor planet-hosting stars. The Kepler and HARPS samplesV. Zh. Adibekyan, E. Delgado Mena, S. G. Sousa, N. C. Santos, G. Israelian, J. I. González Hernández, M. Mayor and A. A. HakobyanA&A, 547 (2012) A36DOI: https://doi.org/10.1051/0004-6361/201220167