@article{EJDE_2012__2012__a72,
     author = {Bailey, Paul B. and Zettl, Anton},
     title = {Sturm-Liouville eigenvalue characterizations},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2012},
     year = {2012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2012__2012__a72/}
}