M. Aaboud, G. Aad, B. Abbott, O. Abdinov, B. Ali, K. Augsten, D. Caforio, P. Gallus, M. Havránek, Z. Hubáček et al.: Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector. Journal of High Energy Physics 2018(7), 89 (2018). doi:10.1007/JHEP07(2018)089