@article{702292,
     title = {Oscillation theory of higher-order ordinary and functional differential equations with forcing terms},
     booktitle = {Equadiff 5},
     series = {GDML\_Books},
     publisher = {BSB B.G. Teubner Verlagsgesellschaft},
     address = {Leipzig},
     year = {1982},
     pages = {218-221},
     zbl = {0538.34021},
     url = {http://dml.mathdoc.fr/item/702292}
}

Kusano, Takaŝi. Oscillation theory of higher-order ordinary and functional differential equations with forcing terms, dans Equadiff 5, GDML_Books,  (1982), pp. 218-221. http://gdmltest.u-ga.fr/item/702292/