The Milky Way has no in-situ halo other than the heated thick disc - Composition of the stellar halo and age-dating the last significant merger with Gaia DR2 and APOGEE
P. Di Matteo, M. Haywood, M. D. Lehnert, D. Katz, S. Khoperskov, O. N. Snaith, A. Gómez and N. Robichon