On some approximate methods concerning the operatorsT* T

The method of orthogonal projection in potential theory

Hermann Weyl · Duke Mathematical Journal · 1940 · 328 citations

Natural Sciences, Mathematics, Physics +13

On the Upper and Lower Bounds of Eigenvalues

Tosio Kato · Journal of the Physical Society of Japan · 1949 · 259 citations

Natural Sciences, Computer Systems, Vibration +7

On Differential Operators in Hilbert Spaces

Kurt Friedrichs · American Journal of Mathematics · 1939 · 67 citations

Natural Sciences, Mathematics, Physics +13

The Determination of Upper and Lower Bounds for the Solution of the Dirichlet Problem

Harvey J. Greenberg · Journal of Mathematics and Physics · 1948 · 44 citations

Natural Sciences, Mathematics, Physics +10

Upper and Lower Bounds for the Solution of the First Bi‐harmonic Boundary Value Problem

J. B. Díaz, Harvey J. Greenberg · Journal of Mathematics and Physics · 1948 · 26 citations

Engineering, Mechanical Engineering, Computational Mechanics +7