003980000a22001570004500650002000000082002300020530000600043100002300049245007900072260003600151260000900187041000800196300001300204942000800217999001500225  aWater economics  a333.913bP745gcUN  aM  aPlusauellec, Herve  aThe Gergia irrigation scheme in Sudan; objectives, design, and Performance  aWashington,D.C.bThe World Bank  c1990  aEng  avii,90p.  cGEN  c6893d6893