?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aulast=Chabe-Ferret&rft.aufirst=Sylvain&rft.au=Chabe-Ferret%2C+Sylvain&rft.date=20+June+2011&rft.title=Estimating+the+causal+effects+of+the+French+agro-environmental+schemes+on+farmers'+practices+by+difference+in+difference+matching&rft.genre=proceeding