00326    a2200109   4500001001000000005001700010008004100027245003300068100002500101700001700126773007300143ART_1744520260410161923.0260409a                                 10aThe economic gradient method1 aBailey, Elizabeth E.1 aWillig, R.D.0 tThe American Economic Reviewg- Vol. 69, Nº 2 (mayo 1979)wREV16190