Kengo Nakajima OpenMP / MPI Hybrid vs. Flat MPI on the Earth Simulator: Parallel Iterative Solvers for Finite Element Method. 486-499 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2858&spage=486 2003 conf/ishpc/2003 ISHPC db/conf/ishpc/ishpc2003.html#Nakajima03