c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission lines F. Lahuis, E. F. van Dishoeck, J. K. Jørgensen, G. A. Blake and N. J. Evans II A&A, 519 (2010) A3 Published online: 06 September 2010 DOI: 10.1051/0004-6361/200913957