Here is what Find-my-Past states about their version of PERSI: “The Periodical Source Index is compiled quarterly by the Allen County Public Library in Fort Wayne, Indiana, and will be simultaneously updated on findmypast. Along with these updates, findmypast is also working to provide access to the same articles indexed in PERSI through our site. Images from PERSI-indexed articles are regularly added every month.” http://search.findmypast.com/search-world-records/periodical-source-index