You seem to be right: I just picked one, “Xerox Star”, and it is copied from Wikipedia with a couple of changes: “was” → “is”, “mouse” → “mouse (two-button)”

I think that putting attributions on each entry would be too distracting, I’d rather keep the clean style that focuses on the content, but there should be some attribution in the page footer.

Edit: Wow, also the pictures are lifted without attribution as noted in this other post: https://news.ycombinator.com/item?id=32093743