Dynamics of the 6.7 and 12.2 GHz methanol masers around Cepheus A HW2 K. J. E. Torstensson, H. J. van Langevelde, W. H. T. Vlemmings and S. Bourke A&A, 526 (2011) A38 Published online: 17 December 2010 DOI: 10.1051/0004-6361/201015583