Python official site
https://www.python.org

Python module index
https://docs.python.org/3/py-modindex.html

Python Installing Packages
https://packaging.python.org/en/latest/tutorials/installing-packages/

Python Package index
https://pypi.org/

Intro to Python Tutorial
https://python-course.eu/python-tutorial

Learn Python - Free Interactive Python Tutorial.
https://www.learnpython.org

Python Special Variables and Methods.
http://exampleprogramming.com/specialvars.html

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

Python Tutorial.
https://www.tutorialspoint.com/python/index.htm

Python Tutorial.
https://www.pythontutorial.net

Python Tutorial - Learn Python programming
https://www.programiz.com/python-programming

Python Tutorial | Learn Python Programming, GeeksforGeeks.
https://www.geeksforgeeks.org/python-programming-language

Python Tutorials – Real Python, Real Python.
https://realpython.com

Python Tutorials: Learn Python Step-by-Step.
https://www.tutorialsteacher.com/python

Python Tutorial, w3resource,
https://www.w3resource.com/python/python-tutorial.php

NumPy - The fundamental package for scientific computing with Python
https://numpy.org/

Nick Coghlan’s Python Notes
http://python-notes.curiousefficiency.org/en/latest 

L. Team, Python Error Types and Exceptions: The Ultimate Tutorial
https://sdsclub.com/the-ultimate-tutorial-on-python-error-types-and-exceptions

Program Arcade Games With Python And Pygame.
http://programarcadegames.com

Introduction to Data Types: Static, Dynamic, Strong & Weak
https://www.sitepoint.com/typing-versus-dynamic-typing

What is Namespace in Python?
https://www.pythonforbeginners.com/basics/what-is-namespace-in-python.

What are iterator, iterable, and iteration?, Stack Overflow
https://stackoverflow.com/q/9884132

Python Programming Tutorials [Beginners + Advanced] - Python Guides
https://pythonguides.com/python-programming

S. Demetriadis, PytoLearn, School of Informatics.
http://pytolearn.csd.auth.gr/index.html