@article{JFAA_2001__7_4_59683,
     author = {Xionghui He and Hans Volkmer},
     title = {Riesz {Bases} of {Solutions} of {Sturm-Liouville} {Equations.}},
     journal = {The journal of Fourier analysis and applications [[Elektronische Ressource]]},
     pages = {297--308},
     publisher = {mathdoc},
     volume = {7},
     number = {4},
     year = {2001},
     zbl = {0982.42022},
     url = {http://geodesic.mathdoc.fr/item/JFAA_2001__7_4_59683/}
}