Advise between two books

Hi, I'm new on BSD systems .
I have one question, I read various threads but I didn't find an answer for me .
I have intermediate knowledge of the Linux distributions and I would pass to BSD systems, in this case FreeBSD .
I have a doubt about these two books :
1) FreeBSD Handbook of course :D , I read that is the best documentation for FreeBSD .
2) The Design and Implementation of the FreeBSD - Marshall Kirk McKusick, George V. Neville-Neil, Robert N. M. Watson .

What's the best to start in FreeBSD ? I don't know if the official documentation is only a reference or even a good starting point .
Sorry if it's a stupid question but I would to start with a good guide .

Have a nice day .
To start use the handbook. "The Design and implementation of FreeBSD" is a book more aimed at developers, not users.
If or when you get to the stage where the deep inner workings of BSD are important to you, Kirk's books are certainly excellent, and pretty much the definitive paper guide to the original bits of BSD and FreeBSD.

The handbook is generally pretty good, but don't forget man(1). Other than the source itself, it is the definitive reference manual for many things inside FreeBSD, covering many things not present in the handbook. There's also a few bits and pieces in /usr/share/doc.
Yes, I will read the man page, for example, it was my unique reading about Debian :D .
Personally, but this is just me, I'd start with the FreeBSD Handbook before buying any other stuff. This is the Internet age we're in and there's honestly hardly anything which you can't find online.

Another very important detail is that the FreeBSD documentation itself, the manualpages, are not to be compared with those found on Linux. On FreeBSD a manualpage is more than often all you need to get started with a program or to learn about specific parts of the system.

Wonder what /etc/rc.conf does? rc.conf(5) will tell you, it has a manualpage. Maybe you'd like to know more about the FreeBSD directory hierarchy. Guess what: hier(7) has you covered. Or maybe a bit more obvious: ports(7), security(7), intro(1) and of course my favorite: man(1) (the classic man man command ;)).

Also noteworthy is that the manualpages are more than often concise. On the latest Debian I can check the hosts manualpage, only to be redirected to a non-existing manualpage for named (section 8). That is something which hardly happens on FreeBSD and what makes this whole thing so unique in my opinion; it works in a true Unix-like fashion, you need to be able to rely on manualpages, and you can.

And if you need more information you may also find it either in the previously mentioned handbook, the /usr/share/doc directory for the base system and /usr/local/share/doc for the ports collection (the software which you install 'on top' of your system).