@article {BenGolLie05,
    AUTHOR = {Benzi, Michele and Golub, Gene H. and Liesen, J{\"o}rg},
     TITLE = {Numerical solution of saddle point problems},
   JOURNAL = {Acta Numer.},
  FJOURNAL = {Acta Numerica},
    VOLUME = {14},
      YEAR = {2005},
    NUMBER = {},
     PAGES = {1--137},
}