Penguins with charm and quark–hadron duality M. Beneke, G. Buchalla, M. Neubert and C. T. Sachrajda Eur. Phys. J. C, 61 3 (2009) 439-449 Published online: 08 April 2009 DOI: 10.1140/epjc/s10052-009-1028-9