On the Baldwin effect of He ii emission lines in WR (WN) stars J. I. van Gent, H. J. G. L. M. Lamers, A. de Koter and P. W. Morris A&A, 372 3 (2001) 963-980 Published online: 15 June 2001 DOI: 10.1051/0004-6361:20010534