This time I want to share with you all a very interesting site full of resources:
https://javarevisited.blogspot.com/
the name could be lead only to java, but I ensure you that it's, yeah, a normal blogspot site, but despite the outward appearance the topics covered are many and all interesting.
Moreover, in each article there is almost always a link to an external resource, a site, a book to consult.
Happy Hacking!
