Specification by Example is a book that brings together practices such as BDD, ATDD, etc. into one work. The recurrent theme behind it is how many teams have evolved their testing practices over time to reflect the system specification as living documentation, using tests written in abstract, high level language to that effect.
Gojko Adzic identifies 7 different process patterns that seem to be in common with the teams he interviewed for writing this book: Deriving scope from goals, specifying collaboratively, illustrating using examples, refining the specification, automating validation without changing specifications, validating frequently and lastly evolving a documentation system.
The book is intentionally written to describe this process from a high level point of view, so it doesn't really get into the "how to do it" from a technical perspective. It does comment on technical challenges the various teams he interviewed faced but that's about it.
All in all, even though the book was published almost 10 years ago it still packs a lot of goodness in it as the high level process description is still applicable nowadays. There's an appendix highlighting several tools and this is probably a dated aspect of the book.
Nonetheless, a good starting point. And feel free to skip the case studies at the very last chapter. They were fillers more than anything.