Parent is too circumspect to admit that the book is very, very well written, beautifully designed, and free to HN users. No relation to author, just followed link.
I've read it and it's a good book. However, I'd like to take the opportunity to point out to the author that there's an English error on the landing page linked above. It should be "Info" not "Infos" since it's not a countable noun.