notes on rietveld method

[Vikrant Chauhan]

Hello everyone,
                I am a novice crystallographer ( so to say )..workingon XPERT PLUS..can somebody tell me where to look for notes on rietveld method (online) ..coz wherever I look its all about some other programs for rietveld fitting , analysis etc...I wish to write my own someday .

Kindly do the needful..Thanking you in anticipation.

Vikrant Chauhan
Physics udergrad.(4th yr )
Depp of Physics
I I T Kharagpur