33.MAHE L P．Environment and Quality Standards in WTO New Protectionism in Agricultural Trade A European Perspective[R]． Edinburgh：Eight Annua1．Congress of European Agricultural Economists， 1996：36～42 34.LIDDLE B．Free trade and the environment—development system[J]．Ecol Econ，2001，39：21～36
33.MAHE L P．Environment and Quality Standards in WTO New Protectionism in Agricultural Trade A European Perspective[R]．
Edinburgh：Eight Annua1．Congress of European Agricultural Economists， 1996：36～42
34.LIDDLE B．Free trade and the environment—development system[J]．Ecol Econ，2001，39：21～36