@article{ELA_2008__17__a29,
     author = {Kim, In-Jae and Shader, Bryan L.},
     title = {Sign patterns that require a positive or nonnegative left inverse},
     journal = {The electronic journal of linear algebra},
     pages = {209--218},
     publisher = {mathdoc},
     volume = {17},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ELA_2008__17__a29/}
}