Get Scott Duff's red (WWII) book, and then I would strongly suggest actually reading it (grin) - it is still the standard. The others will confuse you and there are many errors to lead you astray - stick to Scott's and ask questions (here).
Here is the link - give him a call. He's a great guy and most of the time he actually picks up the phone himself (which initially took me about 5 phone calls to figure out ...). But be careful on the rest of his site - it will suck your wallet out thru your eyeballs (not his fault, it is just cool stuff - most of it is on consignment and IMHO he is far from the priciest for the stuff he sells). No affiliation other than respect, just a solid recommendation - he won't steer you wrong.
Scott Duff Publications & Historic Martial Arms: M1 Garand, M1 Carbine, M1903, Krag, M1911A1
I also recommend Bruce Canfield's Garand and Carbine book - in it you will find a taste of just about everything. It is a great survey book and will lead you in directions that you didn't know existed.
http://www.scott-duff.com/CanfieldM1_M1.jpg_70.JPG
Now from there I will tell you to get Billy Pyle's Gastrap Garand book, but you may want to wait and save your pennies before you get hooked into the "numbered strain" of Garanditis (you'll see ...). Awesome book, but if you get hooked over there it really gets pricey and fast. Great book but it is like playing with nitro-glycerine for a die-hard Garand addict.
http://www.scott-duff.com/225.jpg
That will get you started and then some. Tell Scott that jeff the Bodyman says "Hey".