On the origin of white dwarfs with carbon-dominated atmospheres: the case of H1504+65 L. G. Althaus, A. H. Córsico, S. Torres and E. García-Berro A&A, 494 3 (2009) 1021-1024 Published online: 22 December 2008 DOI: 10.1051/0004-6361:200810761