@article{GDZPPN00253939X,
title = {Symmetric perturbation of a self-adjoint operator},
journal = {Revista colombiana de matematicas},
volume = {7},
year = {1973},
pages = {81-84},
zbl = {0295.47020},
url = {http://dml.mathdoc.fr/item/GDZPPN00253939X}
}
Rao, D. K. Symmetric perturbation of a self-adjoint operator. Revista colombiana de matematicas, Tome 7 (1973) pp. 81-84. http://gdmltest.u-ga.fr/item/GDZPPN00253939X/