On the internal structure of starless cores - II. A molecular survey of L1498 and L1517B M. Tafalla, J. Santiago-García, P. C. Myers, P. Caselli, C. M. Walmsley and A. Crapsi A&A, 455 2 (2006) 577-593 Published online: 04 August 2006 DOI: 10.1051/0004-6361:20065311