@article{GDZPPN002344955,
title = {A generalization of Courant's nodal domain theorem..},
journal = {Mathematica Scandinavica},
volume = {5},
year = {1957},
pages = {15-20},
zbl = {0077.30101},
url = {http://dml.mathdoc.fr/item/GDZPPN002344955}
}
PEETRE, JAAK. A generalization of Courant's nodal domain theorem... Mathematica Scandinavica, Tome 5 (1957) pp. 15-20. http://gdmltest.u-ga.fr/item/GDZPPN002344955/