@article{EJDE_2002__2002__a145,
     author = {Karakostas,  G.L. and Tsamatos,  P.Ch.},
     title = {Positive solutions and nonlinear eigenvalue problems for retarded second order differential equations},
     journal = {Electronic journal of differential equations},
     year = {2002},
     volume = {2002},
     zbl = {1012.34063},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2002__2002__a145/}
}