@article{GDZPPN002223422, title = {Stability Theorems for Singular Perturbation of Eigenvalues.}, journal = {Manuscripta mathematica}, volume = {35}, year = {1981}, pages = {157-174}, zbl = {0489.47004}, url = {http://dml.mathdoc.fr/item/GDZPPN002223422} }
Greenlee, W.M. Stability Theorems for Singular Perturbation of Eigenvalues.. Manuscripta mathematica, Tome 35 (1981) pp. 157-174. http://gdmltest.u-ga.fr/item/GDZPPN002223422/