@article{PIM_1979_N_S_25_39_a32,
     author = {Cheh-Chih Yeh},
     title = {Nonoscillation {Of} {Nonlinear} {Retarded} {Differential} {Equations}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {240 },
     publisher = {mathdoc},
     volume = {_N_S_25},
     number = {39},
     year = {1979},
     url = {http://geodesic.mathdoc.fr/item/PIM_1979_N_S_25_39_a32/}
}