Hints for 1st APR

http://www.cliffsnotes.com/study_guide/Economic-Analysis.topicArticleId-9789,articleId-9726.html

http://levilovesenglish.blogspot.com/2010/12/pros-and-cons-of-agricultural-subsidies.html

http://www.freeeconhelp.com/2011/10/why-marginal-benefit-equals-marginal.html