(1966). Perturbation theory for linear operators.
Lua i Stíl Chicago (17ú heag.)Perturbation Theory for Linear Operators. 1966.
Lua MLA (9ú heag.)Perturbation Theory for Linear Operators. 1966.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.