Since you want something in the same line of Effective Java the following two books are very similar:
More Effective C#
In both cases you are creating what's called a closure. Essentially, count is being wrapped in a class and that class is being used by the lambda expression.
Bill Wagner has a great book called More Effective C# and he has a blog post that describes closures in more detail.
Effective C# and More Effective C# by Bill Wagner come highly recommended