AXIALLY SYMMETRIC GRAVITATIONAL FIELDS. I. STATIC SOLUTIONS OF THE VACUUM EINSTEIN EQUATIONS ArticleGutsunaev Ts.I., Hassan N.Sh., Elsgolts S.L.Gravitation and Cosmology. Vol. 8. 2002. P.. 249-260
ON THE CALCULATION OF BOUNDS FOR THE SPECTRUM OF A SYMMETRIC MATRIX ArticleSukhinin M.F.Журнал вычислительной математики и математической физики. 2002.