K-band spectroscopy of pre-cataclysmic variables C. Tappert, B. T. Gänsicke, L. Schmidtobreick, R. E. Mennickent and F. P. Navarrete A&A, 475 2 (2007) 575-583 Published online: 02 July 2007 DOI: 10.1051/0004-6361:20077679