[flohofwoe]

On Wayback machine references to this post (a much shorter version though) go back to 1998, this is the oldest reference:

https://web.archive.org/web/19980206223800/https://www.norvi...

[cubefox]

So he changed the text as time went on, since the 1998 version doesn't reference Khan Academy. Though the "(1998)" might still be justified if the changes are minor.