This reference also gives a background of the main ideas of IFT. In my talk. I will go further and discuss the possibilities to use IFT on nonlinear control problems.
Iterative feedback tuning: theory and applications
Halmarsson, H.; Gevers, M.; Gunnarsson, S.; Lequin, O.

IEEE Control Systems Magazine , Volume: 18 Issue: 4, Aug. 1998 Page(s): 26 -41

The paper can be obtained electronically from IEEE. Go to the web page
http://ieeexplore.ieee.org/lpdocs/epic03/authors.htm
and search for Halmarsson (the author's name is actually Hjalmarsson but you have
to give it misspelled since the have it misspelled in the database).