@article{10_4064_ap_42_1_103_113,
     author = {Philip Hartman},
     title = {On the monotonicity of nonnegative solutions and the uniqueness of eigenvalues},
     journal = {Annales Polonici Mathematici},
     pages = {103--113},
     publisher = {mathdoc},
     volume = {42},
     number = {1},
     year = {1983},
     doi = {10.4064/ap-42-1-103-113},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-42-1-103-113/}
}