HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters - The role of blue horizontal branchesS. Perina, S. Galleti, F. Fusi Pecci, M. Bellazzini, L. Federici and A. BuzzoniA&A, 531 (2011) A155DOI: https://doi.org/10.1051/0004-6361/201117028