I knew you couldn’t copyright or trademark a book title, but until recently, I never realized you could trademark a series title. Then I saw a discussion on KBoards that mentioned it. (Sorry, can’t find the thread again.)
I contacted my local trademark attorney, and we filed the paperwork. It’s dead simple. You need to have at least two books in the series published (to establish it as a series), and you need to show the mark in use. I sent him a link to one of my Amazon book pages, which was sufficient.
As you can see, it’s not on the book cover, which I thought might be an issue, but it wasn’t.
The whole thing, including filing fee and attorney’s fee was $675. That might sound like a lot for a self-published author, and it is, but I plan to write lots of books in the series, and I only have to pay this once. I figured it was worth it.
This trademark is only for the e-version. Technically, when I release the paper version, it’s not covered, but, according to my attorney, for practical purposes, it is. I’m good with that.
The fun part for me about self-publishing is everything that I’m learning along the way.