The stellar content, metallicity and ionization structure of HII regions N. L. Martín-Hernández, R. Vermeij, A. G. G. M. Tielens, J. M. van der Hulst and E. Peeters A&A, 389 1 (2002) 286-294 Published online: 14 June 2002 DOI: 10.1051/0004-6361:20020528