@article{03798227,
title = {Oscillations of n-th order retarded differential equations.},
journal = {Publications de l'Institut Math\'ematique. Nouvelle S\'erie},
volume = {29(43)},
year = {1981},
pages = {293-297},
zbl = {0506.34053},
language = {en},
url = {http://dml.mathdoc.fr/item/03798227}
}
Yeh, Cheh-Chih. Oscillations of n-th order retarded differential equations.. Publications de l'Institut Mathématique. Nouvelle Série, Tome 29(43) (1981) pp. 293-297. http://gdmltest.u-ga.fr/item/03798227/