@article{1195513469,
author = {Nambu, Takao},
title = {Degenerate self-adjoint perturbation in Hilbert space},
journal = {Proc. Japan Acad. Ser. A Math. Sci.},
volume = {63},
number = {9},
year = {1987},
pages = { 379-381},
language = {en},
url = {http://dml.mathdoc.fr/item/1195513469}
}
Nambu, Takao. Degenerate self-adjoint perturbation in Hilbert space. Proc. Japan Acad. Ser. A Math. Sci., Tome 63 (1987) no. 9, pp. 379-381. http://gdmltest.u-ga.fr/item/1195513469/