Hi,

IMO, most recent books even online manuals are devoted to a one particular distribution - so it is not only a hell of dependencies (you will learn very quickly what that's mean) - but also the hell of distributions. All distributions share the same core - but out of this there are many differences. I started to teach myself at ibiblio.org. There are - today someone might say - outdated books - but at least you will understand many things which are common to all distributions. Depending on what do you really want to learn - pick up carefully a distribution. There is no way to learn without using. I advice to install virtually several to have feel and look. Next to choose one or two. Stick with them for a while. Then you will have a base to learn.

Unlike Windows or MacOS, the graphical environment under Linux is not monolithic, hence the proliferation of desktop environments (DEs). Pick a distro (ideally, the distro your university will have you use) and try out the live cds for each of their different DEs. Once you find one you like, you can install it on your computer and start exploring further.

Look at this also:
http://distrowatch.com/dwres.php?resource=major

This is called "top ten", but it's not quite the same as what appears in their "hit list".

It needs saying, with any flavor of Linux, you will find tons of reading materials online and printed. These materials will cover the tiniest details and the largest of big-picture views. Some other software offers "here is an on screen button. push it and it changes colors" class publications at a much higher cost that download time.
Most of the paper book publishers also offer Linux topic titles in various e-Book formats as well.

It is often impossible to use online docs when you are trying to fix a computer that is down or otherwise
off the network. (grin)

Favorite Error Message:
"Your system has crashed.
Consult help files for detailed explanation."

Cheers,
~~~ 0;-Dan