https://www.nber.org/system/files/working_papers/w31661/w31661.pdf
Authors. Alfaro, L. & Chor, D
Venue. NBER Working Paper 31661
How the Institute flags it
frontier 1 time established 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.