JAVA

https://www.java.com/en/

https://www.oracle.com/hu/index.html

https://www.oracle.com/java/

PYTHON

https://www.python.org/

Python (programming language)

https://en.wikipedia.org/wiki/Python_%28programming_language%29

https://www.w3schools.com/python/

https://www.tutorialspoint.com/python/python_basic_operators.htm

https://www.codecademy.com/learn/learn-python

JavaScript

https://www.javascript.com/

https://www.w3schools.com/Js/

https://en.wikipedia.org/wiki/JavaScript

https://developer.mozilla.org/en-US/docs/Web/javascript

https://video.search.yahoo.com/search/video?fr=mcafee_uninternational&p=Javascript#id=1&vid=433d7619d06ec1147353182a04791dc9&action=click

https://video.search.yahoo.com/search/video?fr=mcafee_uninternational&p=Javascript#id=3&vid=e695feffa704f9ab7e7be15c6c666365&action=view

https://video.search.yahoo.com/search/video?fr=mcafee_uninternational&p=Javascript#id=5&vid=f6159d19a118be50d6e234ce757072de&action=view

C++

https://www.cplusplus.com/

https://en.wikipedia.org/wiki/C%2B%2B

https://www.cplusplus.com/doc/tutorial/

Visual C++ in Visual Studio 2015

https://msdn.microsoft.com/en-us/library/60k1461a.aspx

https://www.tutorialspoint.com/cplusplus/

https://www.youtube.com/watch?v=Rub-JsjMhWY

https://docs.microsoft.com/en-us/cpp/?view=vs-2017

C#

https://en.wikipedia.org/wiki/C_Sharp_%28programming_language%29

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/

https://docs.microsoft.com/en-us/dotnet/csharp/

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator

https://csharp.net-tutorials.com/

https://www.tutorialspoint.com/csharp/csharp_overview.htm

https://mva.microsoft.com/en-us/training-courses/c-fundamentals-for-absolute-beginners-16169?l=Lvld4EQIC_2706218949

PHP

https://php.net/

https://php.net/manual/en/intro-whatis.php

https://php.net/manual/en/tutorial.php

https://www.w3schools.com/php/

https://windows.php.net/download/

Perl

https://www.perl.org/

https://en.wikipedia.org/wiki/Perl

https://www.tutorialspoint.com/perl/

https://learn.perl.org/tutorials/

https://www.britannica.com/technology/Perl