https://materias.df.uba.ar/rga2019c2/files/2019/11/MT.pdf
Authors. Morris & Thorne
Venue. Am. J. Phys. 56:395 — university-hosted PDF (fetch returned bibliographic front matter only; do not quote text from this link)
How the Institute flags it
established 2 times speculative 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.