@article{NUMA_1990__57_6-7_133450,
     author = {Roland Freund},
     title = {On {Conjugate} {Gradient} {Type} {Methods} and {Polynomial} {Preconditioners} for a {Class} of {Complex} {Non-Hermitian} {Matrices.}},
     journal = {Numerische Mathematik},
     pages = {285--312},
     publisher = {mathdoc},
     volume = {57},
     number = {6-7},
     year = {1990},
     zbl = {0702.65034},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__57_6-7_133450/}
}