Documentary Storytelling: Making Stronger and More Dramatic Nonfiction Films by Sheila Curran Bernard. Here's a tiny excerpt from the chapter, "Story Basics":
"Don't be confused by the fact that festivals and film schools commonly use the term 'narrative' only to describe works of dramatic fiction. Most documentaries are also narrative, which simply means they tell stories (whether or not those stories are also narrated is an entirely different issue). How they tell those stories and what stories they tell separates the films into subcategories such as genre or style, from cinéma vérité to film noir."
The title above is directly linked to the publisher. A PDF of the first chapter is available for review at no charge.