The research files on Operation Green were preserved at Iowa State University Library.

Evidence

When Knudson moved on from Des Moines, he left his research files at the Iowa State University Library for future inquirers, and a kind librarian there sent me scans of the material on hog cholera, which included Knudson’s notes and transcriptions. — Nicholson Baker, Baseless- My Search for Secrets in the…, 457

Categorization

• corroborated: 3 independent passages support this claim — Nicholson Baker, Baseless- My Search for Secrets in the…, 457