@article{10_1017_S0017089510000716,
     author = {O'REGAN, DONAL and ORPEL, ALEKSANDRA},
     title = {EIGENVALUE {PROBLEMS} {FOR} {SINGULAR} {ODES}},
     journal = {Glasgow mathematical journal},
     pages = {301--312},
     year = {2011},
     volume = {53},
     number = {2},
     doi = {10.1017/S0017089510000716},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089510000716/}
}