There are a couple great spinning books that are out-of-print in paper, but you can still get as digital books.
Jacey Faulkner's Spin Art: Mastering the Craft of Spinning Textured Yarns, and Amy King's Spin Control:Techniques for Spinning the Yarn You Want. If you really want the paper versions, you can still find them from used book sellers.
If you are a new spinner, I highly reccomend Maggie Casey's Start Spinning, available as an e-book, and a paper book.
I own and use all three books in both formats. I've grown to really like having electronic books on my tablet for quick reference, and for comaparing ideas between authors. I never thought I would.
Of course, my book Yarnitecture is avialible in paper and e-book format.
To those of you celelbrating U.S. Thanksgiving this week, Happy Thanksgiving! Don't forget to wear your strechy pants.
To everyone, I am so grateful for your support, reading all of my words, taking my classes,and buying my book!