@article{03946666,
title = {Comparison theorems for fourth order differential equations.},
journal = {International Journal of Mathematics and Mathematical Sciences},
volume = {9},
year = {1986},
pages = {105-109},
doi = {10.1155/S0161171286000133},
zbl = {0589.34028},
language = {en},
url = {http://dml.mathdoc.fr/item/03946666}
}
Etgen, Garret J.; Taylor, Willie E.jun. Comparison theorems for fourth order differential equations.. International Journal of Mathematics and Mathematical Sciences, Tome 9 (1986) pp. 105-109. doi : 10.1155/S0161171286000133. http://gdmltest.u-ga.fr/item/03946666/