@ARTICLE{
author={Agarwal Ravi P,Grace Said R,Manojlovic Jelena V},
year={2006},
title={On the oscillatory properties of certain fourth order nonlinear difference equations},
journal={JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS},
volume={322},
number={2},
pages={930-956},
document_type={Article},
} 

@ARTICLE{
author={Agarwal Ravi P,Grace Said R,Manojlovic Jelena V},
year={2006},
title={Oscillation criteria for certain fourth order nonlinear functional differential equations},
journal={MATHEMATICAL AND COMPUTER MODELLING},
volume={44},
number={1-2},
pages={163-187},
document_type={Article},
}