Collisions in primordial star clusters - Formation pathway for intermediate mass black holes B. Reinoso, D. R. G. Schleicher, M. Fellhauer, R. S. Klessen and T. C. N. Boekholt A&A, 614 (2018) A14 Published online: 06 June 2018 DOI: 10.1051/0004-6361/201732224