A note on the stability and boundedness results of solutions of certain fourth order differential equations

The purpose of this paper is to investigate the asymptotic stability of the zero solution of x((4)) + phi(<(x)double over dot>)(x) triple over dot + f(x, <(x)over dot>)<(x)double over dot> + g(<(x)over dot>) h(x) = 0 with p not equal 0 and the boundedness of all solutions of x((4)) + phi(<(x)double over dot>)(x) triple over dot + f(x, <(x)over dot>)<(x)double over dot> + g(<(x)over dot>) h(x) = 0 with p not equal 0. The results obtained here revise the results in [Demonstratio Math. 31(1) (1998) 87] and improve and includes some results in the relevant literature. (C) 2003 Elsevier Inc. All rights reserved.