> Programming Python from O'Reilly. It helps lift my monitor nicely.

Wow - same with me. Perfect size to match my monitor base! I also keep a 2002(?) copy of "Creating Web Pages for Dummies" to remind me of my roots.

>> Honestly, I've yet to find a physical book that has proven to be a useful reference in the long run. Programming languages just change too quickly; it's the web or the code.

In the old days you might use a compiler for 3-4 years. Nowadays, something you'd buy a book on could change versions in less than a year. Anything I bought in the early days of XCode/iOS was obsolete before I knew it. I bought a JQuery book and it was already a point release behind.

"I've yet to find a physical book that has proven to be a useful reference in the long run"

Me either, but how else do you signal to other programmers how knowledgeable and well-rounded you are in the field?

probably with the quality of your work? :)

Your collection of PDFs :-)

For real study, I find books better than online references, even if many do go out of date quite quickly these days. Something about printed words on paper that helps with focus. Online references are great for quick questions, but when I want to take some time to understand something in depth, I always prefer a book, or if one is not available, I will print the online material for study.

I have 2 of the 7 books of the X Window Programming Reference in that role.

Apart from K&R, there are very few programming books which are worthwhile; up to about 10 years ago the ORA series were worthwhile, but nowadays especially with StackExchange it's just far better to get the one fragment of information you need in a handy searchable pasteable internet format.

(Non-programming book recs: recently The Man Who Stole Portugal (non-fiction, surprisingly relevant to crypto) and The Time Of Gifts (biography, extravagantly written, requires checking wikipedia every 5 dozen words unless you have a really excellent knowledge of European history)