The latest J.R.R. Tolkien project lasted six years, more than half as long as the author needed to complete his Lord of the Rings trilogy. Getting permission to release a book in electronic form can be as hard — or harder — than writing it. “The Tolkien estate wanted to be absolutely confident that e-books were not something ephemeral,” says David Brawn, publishing operations director at HarperCollins UK, which announced last week that the late British author’s work — among the world’s most popular — would be available for downloads.