We have a Black Friday E-book sale for Carl's books. There is 40% OFF on our Gumroad shop. The sale is running till next monday.

The offer code to use is: blackfriday

Enter the Gumroad shop here:  https://gumroad.com/carendt

​Direct Discount links: All three books, Book 1, Book 2 or Book 3

Carl's E-books are digital books, delivered by e-mail, in PDF format. You can read them on your computer, phone, tablet, or print them for yourself.