Cătinaş, Emil, and I Păvăloiu. “On Approximating the Eigenvalues and Eigenvectors of Linear Continuous Operators”. Rev. Anal. Numér. Théor. Approx. 26, no. 1 (August 1, 1997): 19–27. Accessed November 22, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1997-vol26-nos1-2-art3.