Gluten is in wheat, rye and barley. Oats doesn't have gluten but becomes cross-contaminated with wheat so you have to make sure the oats are labelled gluten-free.
My library has quite a few books on gluten (cookbooks as well). I'm reading one right now called The Gluten Connection. It connects a lot of autoimmune diseases with gluten not just hashi's.
I haven't gone completely gluten-free yet but I have cut way down. I have an enlarged thyroid where my neck swells up at times. I'm kind of experimenting with what causes it to swell. So far, it does seem to swell more when I eat more gluten.