All our ebooks are flying free with creative commons licenses. Specifically, we use either the Attribution-NonCommercial-ShareAlike 3.0 Unported (CC-BY-NC-SA 3.0 Unported) license, either the Attribution-NonCommercial-NoDerivs 3.0 Unported (CC-BY-NC-ND 3.0 Unported) license, according to the author's choice. Therefore, the readers can fully enjoy our ebooks, since they are allowed to share them with their friends, photocopy them, upload them in any website or blog, modify them in any way they wish and, ultimately, create a new context, enriched with their thoughts and ideas (please note that only the ebooks with the CC-BY-NC-SA 3.0 Unported license can be modified).