The CN isotopic ratios in comets J. Manfroid, E. Jehin, D. Hutsemékers, A. Cochran, J.-M. Zucconi, C. Arpigny, R. Schulz, J. A. Stüwe and I. Ilyin A&A, 503 2 (2009) 613-624 Published online: 02 July 2009 DOI: 10.1051/0004-6361/200911859