@article{MR_1987_33_a1,
     author = {Elias A. Lipitakis and  George A. Gravvanis},
     title = {The {Convergence} rate and {Complexity} of {Precondotioned} {Iterative} methods based on {Approximate} finite {Element} matrix {Factorization}},
     journal = {M\ensuremath{\alpha}\ensuremath{\theta}\ensuremath{\eta}\ensuremath{\mu}\ensuremath{\alpha}\ensuremath{\tau}\ensuremath{\iota}\ensuremath{\kappa}\ensuremath{\acute\eta} E\ensuremath{\pi}\ensuremath{\iota}\ensuremath{\theta}\ensuremath{\varepsilon}\ensuremath{\acute\omega}\ensuremath{\rho}\ensuremath{\eta}\ensuremath{\sigma}\ensuremath{\eta}},
     pages = {11--23},
     year = {1987},
     volume = {33},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/MR_1987_33_a1/}
}