@article{EJDE_2004__2004__a15,
     author = {Mingarelli,  Angelo B.},
     title = {Characterizing degenerate {Sturm-Liouville} problems},
     journal = {Electronic journal of differential equations},
     year = {2004},
     volume = {2004},
     zbl = {1076.34025},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2004__2004__a15/}
}