@article{GDZPPN002200996,
title = {On the completeness of eigenfunctions and associated functions of irregular multipoint eigenvalue-problems.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {346},
year = {1984},
pages = {36-47},
zbl = {0514.34014},
url = {http://dml.mathdoc.fr/item/GDZPPN002200996}
}
Freiling, Gerhard. On the completeness of eigenfunctions and associated functions of irregular multipoint eigenvalue-problems.. Journal für die reine und angewandte Mathematik, Tome 346 (1984) pp. 36-47. http://gdmltest.u-ga.fr/item/GDZPPN002200996/