Hα line profiles for a sample of supergiant HII regions - I. The main spectral component M. Rozas, M. G. Richer, J. A. López, M. Relaño and J. E. Beckman A&A, 455 2 (2006) 539-547 Published online: 04 August 2006 DOI: 10.1051/0004-6361:20054388