The puzzling behavior of HNCO isomers in molecular clouds N. Marcelino, S. Brünken, J. Cernicharo, D. Quan, E. Roueff, E. Herbst and P. Thaddeus A&A, 516 (2010) A105 Published online: 22 July 2010 DOI: 10.1051/0004-6361/200913806