On the systematics of asteroseismological mass determinations of PG 1159 stars L. G. Althaus, A. H. Córsico, S. O. Kepler and M. M. Miller Bertolami A&A, 478 1 (2008) 175-180 Published online: 12 November 2007 DOI: 10.1051/0004-6361:20078524