There are a few, the best are:
1. Hypoglycemia (Jeraldine Saunders): Lots of good info and case studies, but there are some mistakes in it. Previously title Hypoglycemia: The Disease Your Doctor Won't Treat. It will be cheaper to find that version online, there is little difference in the new version.
2. Hypoglycemia: A New Approach: This one has a lot of good info concerning organics and such but it is incredibly wrong when it comes to certain issues concerning what to eat and what human beings are supposed to eat. He, for example, erroneously assumes that after 10,000 years of eating grain our bodies are geared to eat it now. Sorry, can't sidetrack millions of years of development in that short of time, what you're seeing now in terms of disease due to diets high in carbohydrates is due to this, we haven't adapted yet and may never.
3. Hypoglycemia For Dummies: This one has a lot of good info too, but also a number of mistakes. Good general reference.
4. Sugar Blues: Not so much for hypoglycemia as it is for the history of why the American diet is so crappy. Great read.
5. The Do's and Don'ts of Hypoglycemia: Stay FAR AWAY from this book, it's awful and doesn't deserve to be in print. One of the WORST things you'll ever read. There is some okay info in it, but it's tailored more for complete morons and people that don't have a clue. Hardly gives any indication of how you should be eating or what you should be eating. For example, one chapter has stuff in it like "DO wear appropriate socks before working out." What? What the hell does that have to do with anything? There are even comments about doing your nails and such, it's worthless, don't get it. You're better off in most cases just posting here, but the first few books I mentioned are good to read through.