When you browse to distrowatch.com, the panel on the left hand side of their home page lists "Free Linux Guides" and shows a picture and description of such a book and a link to get it. You have to provide a working email address and make up some bogus information about yourself for the spammers, but then they email you a download link to actually get the book, for free, in pdf format. Every time you refresh the distrowatch.com home page, it presents a different book and (at least for the duration of your session, depending on your browser settings) you don't have to re-enter all of you information for each book.
I downloaded a -bunch- of them recently, though I haven't had time to actually read them yet so I can't say much about the quality - just that the price was a good fit for my budget! Judging only by the covers (ok... the pictures and the titles and descriptions) of these books, I would say there are some that would serve your purpose, at least as a starting point... specifically, there are titles re. Linux, Linux Administration and Samba as well as a ton of other related subjects.
There are several PDF viewers in the repo. I use xpdf. There are probably better ones.
Save some trees and save some money.