Some empirical estimates of the H2 formation rate in photon-dominated regionsE. Habart, F. Boulanger, L. Verstraete, C. M. Walmsley and G. Pineau des ForĂȘtsA&A, 414 2 (2004) 531-544DOI: https://doi.org/10.1051/0004-6361:20031659