The book is distributed completely freely according to copyleft rules. Any part or all of the book may be quoted or printed without permission from the author. Provided that it is distributed free of charge and the text remains unchanged. The development of the ideas contained in the book is also welcome.

To slightly paraphrase Richard Stallman, founder of the free software movement, the Free Software Foundation and the League for Programming Freedom: “I believe that if I like a book, then the golden rule requires so that I can share it with other people who might also like it.”