A quantitative NLTE analysis of visual and ultraviolet spectra of four helium-rich subdwarf O starsM. Schindewolf, P. Németh, U. Heber, T. Battich, M. M. Miller Bertolami, A. Irrgang and M. LatourA&A, 620 (2018) A36DOI: https://doi.org/10.1051/0004-6361/201732140
