@article{EJDE_2008__2008__a68,
     author = {Yuan,  Yanyan and Zhao,  Chenglong and Liu,  Yansheng},
     title = {Positive solutions for systems of nonlinear singular differential equations},
     journal = {Electronic journal of differential equations},
     year = {2008},
     volume = {2008},
     zbl = {1179.34025},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2008__2008__a68/}
}