Cohn, Mike. Agile Estimating and Planning. Upper Saddle River, NJ: Prentice Hall Professional Technical Reference, 2006. Cohn's book contains a more extended discussion of story points, including planning considerations as well as estimation techniques.
Humphrey, Watts S. A Discipline for Software Engineering. Reading, MA: Addison-Wesley, 1995. Chapter 5 of Humphrey's book discusses proxy-based estimation, which he calls the PROBE method, and goes into detail on some supporting statistical techniques. Chapter 5 also discusses fuzzy logic.