Susan Ashworth, Seed to Seed. Best resource book out there in my opinion. Can buy at Southern exposure seeds
Baker creek seeds or Seed Savers Exchange to name a few

Thank you Rodger, I was searching on Amazon and that one was the top of the results list.

I have Ashworth's Seed to Seed and Carol Deppe's Breed Your Own Vegetable Varieties. I prefer Deppe's book, which contains useful information on seed saving, because it is oriented to the needs of the home gardener. The information in Ashworth's book, although it also is intended for the home gardener, appears to be derived mostly from agricultural research and does not offer as much in the way of practical solutions for the home garden environment. Home gardens have different populations of pollinating insects and present different problems regarding isolation distances than the large fields used in agricultural research. Deppe deals with those issues. She also deals with the genetic implications of seed saving. As she says, seed saving is plant breeding. So it's important to take genetics into account.

Jim