Found in 2 comments on Hacker News
Zigurd · 2024-10-22 · Original thread
O'Reilly, for whom I've been a lead author and co-author, did this: https://www.oreilly.com/pub/pr/1042

They call it Founder's Copyright. The also use Creative Commons. The goal is to make out of print books available at no cost.

zootboy · 2023-04-30 · Original thread
You're downvoted because you didn't bother to even look at the copyright citation on the linked Archive.org page. Specifically:

> Copyright-comment

> Scanned under the Creative Commons Founders' Copyright license, per Tim O'Reilly.

Yes, O'Reilly did, in fact, re-license the content for sharing:

https://www.oreilly.com/pub/pr/1042