See Online help in Wikipedia
- (tex)info was one of the first. Stallman seems to have had no model to build on but he may have known Nelson's works (?)
- Norton Guides came later but may have been invented independently (?)
- See http://www.helpmvp.com/MVP-Info/history/ralphnotes and http://www.helpmvp.com/MVP-Info/history/leonotes for history of QuickHelp (OS/2 and MS-DOS) and WinHelp (later replaced by HTML Help in Windows and IPF in OS/2). QuickHelp was also based on MS Advisor. WinHelp technology was also used to create Encarta 1.0 (1993).
- AmigaGuide came later, who knows whether influenced by what?
- DocBook only came in the early 1990s when there was already HTML
