For a list that generally approaches easily accessible on your own, I would put Muqawama's COIN reading list.

Caution: for all the people who HATE population-centric COIN, this reading list is pretty much geared toward it. It has an amazing collection of very good articles as well. If you want to know what is influencing policy in the US government in Afghanistan it is this reading list.

http://www.cnas.org/blogs/abumuqawam...ding-list.html