L. Dessart et P. Crowther, Ionizing power of massive stars in the cores of two giant HII regions: R136A and HD 97950, ASTRO SP SC, 260(1-2), 1998, pp. 177-180
We evaluate the integrated ionizing fluxes in cores of giant HII regions be
low the important continuum edges, considering both O and WR stars. We find
that they contribute in equivalent proportions to the HI and HeI continua,
but that only the hottest O stars emit in the HeII continuum.