Lack of PAH emission toward low-mass embedded young stellar objects V. C. Geers, E. F. van Dishoeck, K. M. Pontoppidan, F. Lahuis, A. Crapsi, C. P. Dullemond and G. A. Blake A&A, 495 3 (2009) 837-846 Published online: 14 January 2009 DOI: 10.1051/0004-6361:200811001