Please download note on the following link:
http://sites.google.com/site/ksopheaktra/Home/Chapter5ProcessModeling.ppt?attredirects=0
http://sites.google.com/site/ksopheaktra/Home/Chapter5-DFD-Bookstore.ppt?attredirects=0
If you have any questions, you can let me know.
Have a good weeken,