Quoth G. Branden Robinson:
Thank you for clarifying. I don't have any Plan 9 source artifacts from that far back; I use "n-t-roff"'s GitHub repository, for which the first commit is dated 12 October 2014.A cursory Google search did not turn up downloadable source archives of any release prior to the fourth edition, though it appears there should be no legal impediment to their distribution[1].
They can be downloaded from https://p9f.org/dl/index.html . -- Humm
