First, is this the right area to post topics on combinatorics? It seemed better than "General Math" to me, but I'm not quite sure this is right either. OK, my question is a general one. I've been trying to calculate some things recently, and it strikes me that what I'm doing is essentially combinatorical. I haven't had any classes in the field, though, which means that at best I'm wandering in the dark. Are there any good *basic* references out there, online or otherwise? Edit: I'm mainly interested in enumeration, for what it's worth. It seems that what I want to learn about is the Pólya enumeration theorem, but looking over what information I found (e.g. MathWorld's entry and a few other online sources) I wasn't able to properly understand it. What do I need to do to get this background?