There was also this one, which was more recent; The Holy Grail: Hhyyrylainen’s Challenge of UC Metalworking Completed and Formalized with 47 Citations!
Edit: It proves up to metal smelting, but not how they would properly shape the metal or any other components of civilization past the point of smelting the metal. As such, Hhyyrylainen’s challenge of a full essay with citations has yet to be completed
Edit 2: Regardless, this is off topic. Back to low oxygen civilizations!