SiO outflows in high-mass star forming regions: A potential chemical clock?A. López-Sepulcre, C. M. Walmsley, R. Cesaroni, C. Codella, F. Schuller, L. Bronfman, S. J. Carey, K. M. Menten, S. Molinari and A. Noriega-CrespoA&A, 526 (2011) L2DOI: https://doi.org/10.1051/0004-6361/201015827