Re: looking for books or notes that talk about how to optimally choose instrument variables in the GMM setting?



The ENTIRE October 2002 issue of Journal of Business and Economic Statistics is on GMM:
http://titania.asa.catchword.org/vl=11323885/cl=15/nw=1/rpsv/cw/vhosts/asa/07350015/v20n4/contp1-1.htm

Although, you'll need access through a database or a direct subscription ($).

Otherwise..
http://fmwww.bc.edu/EC-P/WP545.pdf

(also, check out the extensive list of references)
.