@article{GDZPPN002343371,
title = {On a type of eigenvalue problems for certain elliptic differential operators},
journal = {Mathematica Scandinavica},
volume = {2},
year = {1954},
pages = {267-285},
zbl = {0056.32304},
url = {http://dml.mathdoc.fr/item/GDZPPN002343371}
}
EHRLING, GUNNAR. On a type of eigenvalue problems for certain elliptic differential operators. Mathematica Scandinavica, Tome 2 (1954) pp. 267-285. http://gdmltest.u-ga.fr/item/GDZPPN002343371/