@article{GDZPPN002320479,
title = {Spectrality Criteria for Unbounded Operators with Real Spectrum.},
journal = {Mathematische Annalen},
volume = {255},
year = {1981},
pages = {19-28},
zbl = {0459.47022},
url = {http://dml.mathdoc.fr/item/GDZPPN002320479}
}
Kantorovitz, Shmuel. Spectrality Criteria for Unbounded Operators with Real Spectrum.. Mathematische Annalen, Tome 255 (1981) pp. 19-28. http://gdmltest.u-ga.fr/item/GDZPPN002320479/