Why simple stellar population models do not reproduce the colours of Galactic open clustersA. E. Piskunov, N. V. Kharchenko, E. Schilbach, S. Röser, R.-D. Scholz and H. ZinneckerA&A, 507 1 (2009) L5-L8DOI: https://doi.org/10.1051/0004-6361/200913270
