None, that I know of. I got mine via Amazon. The fastest way is getting a Kindle copy. I’ve got both the paperback & Kindle versions. There are some differences (especially in the first book) between the hard copy & the e-copies. Makes it interesting. I liked the initial book’s spare style & the e-copy version has a lot more exposition in it. Not a bad thing, but it was like watching the original version of Star Wars & then the digitally remastered version with all the extra aliens & effects thrown in later.