PYTHON REFERENCES

1. Online Python Tutor : It is a free educational tool that helps students overcome a fundamental barrier to learning programming: understanding what happens as the computer executes each line of a program's source code. Using this tool, a teacher or student can write a Python program directly in the web browser and visualize what the computer is doing step-by-step as it executes the program.
2. life is short - you need Python!: A blog on Python with tutorials, code, programs, tips and tricks, how-to, book-list, crawler / spider help, data structure and algorithm implementation and many more ... maintained by Tamim Shahriar Subeen, one of the best IT professional in Bangladesh.
3. Python for fun - advanced python codes: This collection is a presentation of several small Python programs. They are aimed at intermediate programmers; people who have studied Python and are fairly comfortable with basic recursion and object oriented techniques. Each program is very short, never more than a couple of pages and accompanied with a write-up.
4. site aims to be both a library of educational materials using Python to teach computer programming, and a virtual meeting place for teachers and students engaged in learning and teaching using Python.  Happy computing!