CALIFA reveals prolate rotation in massive early-type galaxies: A polar galaxy merger origin? A. Tsatsi, M. Lyubenova, G. van de Ven, J. Chang, J. A. L. Aguerri, J. Falcón-Barroso and A. V. Macciò A&A, 606 (2017) A62 Published online: 12 October 2017 DOI: 10.1051/0004-6361/201630218