Homework help needed: Using examples, I have to discuss and evaluate some aspects of greenwashing or astroturfing.

I understand that the two words means a grassroot movement paid by a corporation to push the corporation’s agenda or to make it look good.

I’ve got Bivings Group, Bonner & Associates, Burson-Marsteller on my list to write about. Does anyone have any literature or thoughts to share on the topic? Please feel free to share but be nice. :) Thank you.