[CII] 158 μm emission and metallicity in photon dominated regions M. Röllig, V. Ossenkopf, S. Jeyakumar, J. Stutzki and A. Sternberg A&A, 451 3 (2006) 917-924 Published online: 04 May 2006 DOI: 10.1051/0004-6361:20053845