Werbos's 1988 print account is a second, earlier-dated attestation of the TSP manual's role — narrowing but not closing the single-witness gap on the manual's content

paul-werbostsp-manualbackpropagationhistory-of-mlsourcingsingle-witness

claim-werbos-tsp-manual-first-publication carries an audit_status flagging the manual's content as single-witness: no copy has been located in WorldCat, MIT DSpace, archive.org, or HathiTrust, so only Werbos's own 1993 oral retelling (Talking Nets, MIT Press 1998) attests to what it contained. His 1988 paper — "Generalization of Backpropagation with Application to a Recurrent Gas Market Model," Neural Networks 1:339–356 — adds a second data point from the same author, five years earlier and in a peer-reviewed venue rather than an interview transcript: it describes the manual as where the dynamic-feedback formulation was "embedded (and documented) in user-oriented software," consistent with the 1993 account's "a working command for people to use in statistical analysis."

This narrows, but does not close, the single-witness gap. It is still one person's testimony about the same manual, produced in two different registers fourteen years apart (1988 print, 1993 oral history) — not an independent third-party confirmation of content. The distinction matters because the manual's bare bibliographic existence already has independent attestation: claim-klensin-romberg-1989-sole-source-of-tsp-manual-1977-date shows a 1989 conference chapter cites the same title and authors (albeit with a different publisher name and a different year than Werbos's own citations). No third-party source has been found that describes what the manual's TSP command actually did — only that it existed.