There are numerous resources on the web if you search on "data flow diagrams". I learned DFDs "years ago" from one of Yourdon's associates (DeMarco).

This link is probably one of the better ones (since it's from "the master"):

http://www.yourdon.com/books/msa2e/CH09/CH09.html


>Hi all -
>
>I recently read a very good article (stqemagazine.com May/June 2003) on Requirements. The author was Becky Winant, whose e-mail/web-site is no longer valid. I was hoping to ask her advice on a good book that will teach (without getting esoteric) the proper way to use data flow diagrams.
>
>Anyone have any suggestions (or does anyone know how to contact Becky)? I don't want to 1,000+ page reference.. would prefer a 50 page guide that gets me proficent quickly.
>
>Thanks!