https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0239398
Authors. Abbey, E. J. et al
Venue. PLOS ONE
How the Institute flags it
established 3 times frontier 1 time
This source carries more than one flag across the corpus. That is not an inconsistency to resolve: the same work can be established evidence for one claim and frontier evidence for another, and the flag belongs to the use rather than to the source.