A photon dominated region code comparison study M. Röllig, N. P. Abel, T. Bell, F. Bensch, J. Black, G. J. Ferland, B. Jonkheid, I. Kamp, M. J. Kaufman, J. Le Bourlot et al. (14 more) A&A, 467 1 (2007) 187-206 Published online: 20 February 2007 DOI: 10.1051/0004-6361:20065918