@ARTICLE{
author={Carrella A,Brennan Michael J,Kovacic Ivana N,Waters Timothy P},
year={2009},
title={On the force transmissibility of a vibration isolator with quasi-zero-stiffness},
journal={JOURNAL OF SOUND AND VIBRATION},
volume={322},
number={4-5},
pages={707-717},
document_type={Article},
} 

@ARTICLE{
author={Brennan Michael J,Kovacic Ivana N,Carrella A,Waters Timothy P},
year={2008},
title={On the jump-up and jump-down frequencies of the Duffing oscillator},
journal={JOURNAL OF SOUND AND VIBRATION},
volume={318},
number={4-5},
pages={1250-1261},
document_type={Article},
}