[gaius]

No disrespect intended, but if you have on your CV that you have "written a book" and it turns out not to be an actual book, with an actual publisher, in actual bookstores, it will create a bad impression with most interviewers. You should rephrase it as an "online tutorial" or something.

[thewhitetulip]

Thank you for the advice. I always tend to write a short tutorial, but then people ask, "what made you write the book" or "what's the structure of your book if I want to contribute". That's why I end up writing book. I will keep this tip in mind :-)