@article{1250127492,
author = {Cosner, Chris and Schlinder, Frank},
title = {Upper and lower solutions for systems of second order equations with nonnegative characteristic form and discontinuous nonlinearities},
journal = {Rocky Mountain J. Math.},
volume = {14},
number = {4},
year = {1984},
pages = { 549-558},
language = {en},
url = {http://dml.mathdoc.fr/item/1250127492}
}
Cosner, Chris; Schlinder, Frank. Upper and lower solutions for systems of second order equations with nonnegative characteristic form and discontinuous nonlinearities. Rocky Mountain J. Math., Tome 14 (1984) no. 4, pp. 549-558. http://gdmltest.u-ga.fr/item/1250127492/