@article{EJDE_2009__2009__a77,
     author = {Kwong, Man Kam and Wong, James S.W.},
     title = {An optimal existence theorem for positive solutions of a four-point boundary value problem},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2009},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2009__2009__a77/}
}