Free learning resources for Ada (are they good enough?)

[Dufr <dufriz@gmail.com>]

Hi 

I have decided to start learning Ada.
Online I have found a good number of free learning resources, which include:

* the Ada Programming wikibook (http://en.wikibooks.org/wiki/Ada_Programming)
* the Rosetta Code examples (http://rosettacode.org/wiki/Category:Ada) [very useful]
* the Programming in Ada ebook by cengage.com (http://academic.cengage.com/resource_uploads/downloads/1133190820_323582.pdf)
* Ada Distilled for Ada 2005 by R. Riehle (http://ocw.unican.es/ensenanzas-tecnicas/sistemas-de-tiempo-real/otros-recursos-1/Ada%20Distilled.pdf)

The question now is: do you think that these resources are enough for a beginner, or do you advise me to buy John Barnes' 2005 book as well? I have heard that Barnes' book is very good. That may be so, but it is also somewhat pricey! So I was wondering: would Barnes' book really give a beginner something that is not found in the above resources? If so, what?

Thanks

Dufr