Highly-excited CO emission in APM 08279+5255 at z = 3.9A. Weiß, D. Downes, R. Neri, F. Walter, C. Henkel, D. J. Wilner, J. Wagg and T. WiklindA&A, 467 3 (2007) 955-969DOI: https://doi.org/10.1051/0004-6361:20066117