The molecular gas mass of M 33 P. Gratier, J. Braine, K. Schuster, E. Rosolowsky, M. Boquien, D. Calzetti, F. Combes, C. Kramer, C. Henkel, F. Herpin et al. (8 more) A&A, 600 (2017) A27 Published online: 23 March 2017 DOI: 10.1051/0004-6361/201629300