I have heard of BDD (Behavior Driven Development) just recently, and I liked the idea. since I work mainly with C# and .NET, I found SpecFlow, then learned that SpecFlow uses Gherkin and now I feel lost. Where do you find official documentation that tells you everything you need to know about SpecFlow, the same for Gherkin.
In short: is there a book (not blogs and articles) about developing real life (practical) applications using these tools?