Intra-day variability observations and the VLBI structure analysis of quasar S4 0917+624 X. Liu, L.-G. Mi, J. Liu, L. Cui, H.-G. Song, T. P. Krichbaum, A. Kraus, L. Fuhrmann, N. Marchili and J. A. Zensus A&A, 578 (2015) A34 Published online: 29 May 2015 DOI: 10.1051/0004-6361/201424854