2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102619Significant amounts of hydrogen were found in very hot early-type single WN stars in the SMC and the LMC. Recently, we found similar evidence in the Wolf-Rayet star of a short-period LMC binary. We discuss here the relevance of hydrogen for WR star classification, models, the relation to metallicity, and the GRB progenitors.5 pages, 2 figures, to appear in proc. of the Tartu Workshop, PASP, eds. Lamers, Langer, Nugis, AnnukAstrophysicstext