Singular Perturbation Eigenvalues by a Method of Undetermined Coefficients

Singular perturbation of eigenvalue problems for linear differential equations of even order

1955 • 33 citations

Parametric theory of Δu+k 2 u=0

1957 • 7 citations

Singulare Storungstheorie Partieller Differentialgleichungen

1956 • 3 citations