Treatment of heavy quarks in QCD E. G. de Oliveira, A. D. Martin, M. G. Ryskin and A. G. Shuvaev Eur. Phys. J. C, 73 10 (2013) 2616 Published online: 25 October 2013 DOI: 10.1140/epjc/s10052-013-2616-2