@article{DE_1990_26_7_a14,
     author = {I. E. Kaporin},
     title = {Preconditioning of the method of conjugate gradients for solving discrete analogues of differential problems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1225--1236},
     publisher = {mathdoc},
     volume = {26},
     number = {7},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_7_a14/}
}