<p>I'm quite new to programming, and I was wondering if there is a good source of well-programmed non-standard C code and libraries.</p>

<p>I Googled and didn't find anything. 
I was a bit surprised by this, especially because I used to search for many Python examples and libraries and never had trouble finding anything.</p>

<p>I already use standard libraries such as stdio.c, stdlib.c, and math.c, but I want to use some more specific C modules. A graph processing library, for example. (I don't really need this one, just a collection of C, not C++ or C#, resources and examples)</p>

there is no "centralized" source for C libraries... at least nothing along the lines of CPAN for Perl or the Python Package Index for Python.
Since C is sort of the "default" language for systems programming, it's often unstated that libraries are written for C.  You may want to try Freshmeat.net's
Advanced Search
, since it's centered on Unix software, and there are a lot of C libraries posted there.  For example, here's what I come up with searching for "graph library":
http://freshmeat.net/search/?section=projects&q=%2Bgraph+%2Blibrary
, and you can filter those results by language, license, etc.
(And your English is quite fine!  Which I can't say about all the posters on here :-p)