@article{JRAM_1984__346_152585,
     author = {Gerhard Freiling},
     title = {On the completeness of eigenfunctions and associated functions of irregular multipoint eigenvalue-problems.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {36--47},
     publisher = {mathdoc},
     volume = {346},
     year = {1984},
     zbl = {0514.34014},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1984__346_152585/}
}