@article{EJDE_2006__2006__a69,
     author = {Zhao, Chenglong and Yuan, Yanyan and Liu, Yansheng},
     title = {A necessary and sufficient condition for the existence of positive solutions to singular boundary-value problems of higher order differential equations},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2006},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2006__2006__a69/}
}