The puzzling detection of DCO in the molecular cloud L1689NC. Ceccarelli, C. Vastel, A. G. G. M. Tielens, A. Castets, A. C. A. Boogert, L. Loinard and E. CauxA&A, 381 1 (2002) L17-L20DOI: https://doi.org/10.1051/0004-6361:20011547