@article{EJDE_2000__2000__a27,
     author = {Zhidkov,  P.E.},
     title = {Basis properties of eigenfunctions of nonlinear {Sturm-Liouville} problems},
     journal = {Electronic journal of differential equations},
     year = {2000},
     volume = {2000},
     zbl = {0945.34066},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2000__2000__a27/}
}