(This is the sixth in a weekly series about tools for writers. For the rest of the series, go here.)

In the coming weeks, I’ll cover some free resources for nonfiction book writers, but I’d like to showcase this book as it’s the best non-free tool I’ve found for book proposal writers. (Unless you go to your local library, as I did. Then it’s freer than free! Hooray for libraries!)

Write the Perfect Book Proposal: 10 That Sold and Why dissects ten real proposals, almost line by line, showing what worked and what didn’t, in the opinions of two literary agents who are pretty good at what they do. I haven’t found a book with as many real-world examples as this one, which is why I’d recommend it for some nonfiction writers.

However, some caveats: The book is geared towards what fills most of America’s bookshelves: self-help, business, and advice books. If you’re leaning toward creative nonfiction–memoir, literary journalism, or any other nonfiction writing where the quality of your writing is just as important as your credentials, you won’t find much of use here beyond the basics. Creative nonfiction has really exploded recently (or so I’ve been told), so perhaps the Levines could include at least one creative nonfiction proposal in their next edition.