If you are interested in box sets, you should not miss 5 big tips for authors towards the end of the blog. (bbebooksthailand.com)
Because as soon as you have three books, you can then put out a fourth format which is the three - book box set before your fourth book. (thecreativepenn.com)
You'll also reach listeners who only prefer boxed sets for long distance travel. (medium.com)