How does vitrification affect oocyte viability in oocyte donation cycles? A prospective study to compare outcomes achieved with fresh versus vitrified sibling oocytes. - Solé, M; Santaló, J; Boada, M; Clua, E; Rodríguez, I; Martínez, F; Coroleu, B; Barri, P N; Veiga, A (Human Reproduction, 2013)