P.-O. Loewdin

GROUP ALGEBRA, CONVOLUTION ALGEBRA, AND APPLICATIONS TO QUANTUM MECHANICS.

P.-O. Loewdin, P. Loewdin, 1967 .

Studies in Perturbation Theory. IX. Connection Between Various Approaches in the Recent Development—Evaluation of Upper Bounds to Energy Eigenvalues in Schrödinger's Perturbation Theory

P.-O. Loewdin, P. Loewdin, 1965 .