I always find, whenever I loan Peter Van der Lindens’ “Deep C Secrets: Expert C Programming” book to a fellow colleague, I never get it back. For a while I had 10 or so spare copies to hand out as treats, but now I just refer everyone to this PDF:

https://progforperf.github.io/Expert_C_Programming.pdf

If you’re a C programmer, old or new, and haven’t encountered this book: Stop What You Are Doing And Go Read It! It’s amazing.