A series on understanding property-based testing through implementing a simplified PBT library: Part 1, Part 2, Part 3
"QuickCheck: A Lightweight Tool for Random Testing of Haskell Programs" by Koen Claessen and John Hughes pdf
"An introduction to property-based testing" by Scott Wlaschin link
"Choosing properties for property-based testing" by Scott Wlaschin link
An interesting read about QuickCheck is in Chapter 11 of the excellent Real world Haskell book. The book is freely available online, but do the authors a favor and buy it, it's really worth it also for F# programmers.