@article{article47456b8b,
title   = {On non-linear normal models of a 2-dof model of a structure with quadratic non-linearities},
author = {Balthazar, José Manoel and Brasil, Reyolando Manoel Lopes Rebello da Fonseca},
year = {1995},
doi = {10.1006/jsvi.1995.0224},
journal   = {Journal of Sound and Vibration}
}