Long time readers are aware that one of my favorite books is R. A. Fisher's The Genetical Theory of Natural Selection. It's a touch on the spendy side for a slim, though dense, book. But looking for stuff that's public domain for my Kindle I noticed that you can get the 1930 version free. And it's not just in Kindle formats, you can get it in PDF as well and read it on your computer. I think of TGTNG as somewhat like the Critique of Pure Reason of evolutionary genetics; even if your inclination is to rubbish it, it's an importance place to begin.