@article{1102811271,
author = {Etgen, Garret J. and Pawlowski, James F.},
title = {A comparison theorem and oscillation criteria for second order differential systems.},
journal = {Pacific J. Math.},
volume = {73},
number = {2},
year = {1977},
pages = { 59-69},
language = {en},
url = {http://dml.mathdoc.fr/item/1102811271}
}
Etgen, Garret J.; Pawlowski, James F. A comparison theorem and oscillation criteria for second order differential systems.. Pacific J. Math., Tome 73 (1977) no. 2, pp. 59-69. http://gdmltest.u-ga.fr/item/1102811271/