ttH observation using a combination of Higgs decay channels:
ATLAS "Observation of Higgs boson production in association with a top quark pair at the LHC with the ATLAS detector" paper from 2018: https://arxiv.org/abs/1806.00425
CMS "Observation of ttH production" paper from 2018: https://arxiv.org/abs/1804.02610
CERN LHC seminar on "New CMS measurements of Higgs boson production and decay properties" including ttH Observation (with video recording): https://indico.cern.ch/event/682983/
Most recent ATLAS results for ttH with Higgs→bb:
ATLAS Paper from 2017: "Search for the Standard Model Higgs boson produced in association with top quarks and decaying into a bb pair in pp collisions at √s = 13 TeV with the ATLAS detector": https://arxiv.org/abs/1712.08895
CERN seminar on ATLAS Evidence for ttH production (with video recording): https://indico.cern.ch/event/656771/