@article{GDZPPN002218496,
title = {\"Uber nichtlineare Spektral- und St\"orungstheorie.},
journal = {Manuscripta mathematica},
volume = {12},
year = {1974},
pages = {123-162},
zbl = {0295.47064},
url = {http://dml.mathdoc.fr/item/GDZPPN002218496}
}
Singhof, Wilhelm. Über nichtlineare Spektral- und Störungstheorie.. Manuscripta mathematica, Tome 12 (1974) pp. 123-162. http://gdmltest.u-ga.fr/item/GDZPPN002218496/