@article{01677967,
title = {Quasihyponormal operators and the continuity of the approximate point spectrum.},
journal = {Matematichki Vesnik},
volume = {49},
year = {1997},
pages = {173-176},
zbl = {0999.47501},
language = {en},
url = {http://dml.mathdoc.fr/item/01677967}
}
Djordjević, Slaviša V. Quasihyponormal operators and the continuity of the approximate point spectrum.. Matematichki Vesnik, Tome 49 (1997) pp. 173-176. http://gdmltest.u-ga.fr/item/01677967/