I think its great that we've reached a point in technology that we have people (rather than teams or large companies) creating languages that people can use.
However, if you are looking at books to learn HOW to create a new language you likely haven't answered a more important question: WHY.
Writing something cool is one thing. writing a language is another. What I'm saying is if you are using an ebook to create your language (on the jvm no less) I expect there are several other languages that people have spent YEARS on that I bet would solve most of the issues you could ever have if you learned them a bit better
* The JVM is awesome. But there are lots of "hosted languages" already on that platform that likely will suit most peoples' needs.
How writing a compiler not cool? Just because someone uses a book and targets the JVM, which is a great target platform for a lot several reasons, doesn't mean they aren't doing it just because it's fun.
But why pay $40 for fun when you can do it with free information on the net? If you're doing it for fun, then that information is more than adequate. If, however, you're doing it because you want a real language that people should/would use, then a 44 page PDF is not nearly enough, regardless of how good and densely packed it is. For a real (as opposed to a toy) language, you require theory on language design, on compilers, on programming paradigms, on syntax, on computation models and so much more.
Why are you writing this argument? It has been made on the Internet multiple times, and others spent more time writing their argument and explained your point better.
However, if you are looking at books to learn HOW to create a new language you likely haven't answered a more important question: WHY.