Trigonometric parallaxes of massive star forming regions: G012.88+0.48 and W33 K. Immer, M. J. Reid, K. M. Menten, A. Brunthaler and T. M. Dame A&A, 553 (2013) A117 Published online: 17 May 2013 DOI: 10.1051/0004-6361/201220793