Thanks for the books.
But what I don't understand is why people think so highly of Kali? It's just a debian distro and the tools that you want you can just clone them off github anyway.
The way I see it there's nothing special about Kali Linux, perhaps for the beginners out there Kali is easier to work with.
From my experience of debian (long time ago), although I must say lot of stuff is stable but I always felt like my choices were kind of limited (usually debian distros are not so customisable like Arch/ Gentoo, etc.) and also I couldn't get my hands on the latest bleeding edge software. You have to wait for months to get the latest updates.
Bleeding edge software does matter, let's say a new kernel came out and you wanna try it...it's kind of a nightmare trying to figure out how to make it work without breaking compatibility with other stuff in debian.
TLDR; Not saying Kali is bad but don't think that installing Kali will suddenly make you a super 1337 hacker or that it's the only thing out there. In my opinion the author of ebooks these days use the catchy phrase "Kali Linux" on pretty much everything as a marketing strategy to get people into buying their books. It's certainly working for them so far.