White dwarf-red dwarf binaries in the Sloan Digital Sky Survey - I. Sample definition T. Augusteijn, R. Greimel, E. J. M. van den Besselaar, P. J. Groot and L. Morales-Rueda A&A, 486 3 (2008) 843-853 Published online: 02 January 2008 DOI: 10.1051/0004-6361:20078584