Around 2000 or so, I used to work in tech support for a software company who had like 5000 Windows-based customers and 5 running Solaris. My boss chose me to learn Solaris when the previous “expert” left. I bought this book and started hacking. Good times!
I had a couple of paperbacks back in the day, but they are still lying around where I used to live. The only book that I would still read now is about the Linux kernel, but it’s not O’Reilly and it’s about a deprecated kernel anyway XD