Observations of CO on Saturn and Uranus at millimeter wavelengths: new upper limit determinationsT. Cavalié, F. Billebaud, T. Fouchet, E. Lellouch, J. Brillet and M. DobrijevicA&A, 484 2 (2008) 555-561DOI: https://doi.org/10.1051/0004-6361:20079170