PT - JOURNAL ARTICLE AU - Donald J. Epp AU - James S. Shortle TI - Agricultural nonpoint pollution control: Voluntary or mandatory? DP - 1985 Jan 01 TA - Journal of Soil and Water Conservation PG - 111--114 VI - 40 IP - 1 4099 - http://www.jswconline.org/content/40/1/111.short 4100 - http://www.jswconline.org/content/40/1/111.full