@article{TAM_2004_31_3-4_a9,
     author = {Miroslav Veskovi\'c and Vukman \v{C}ovi\'c},
     title = {On the instability of equilibrium of a mechanical system with nonconservative forces},
     journal = {Theoretical and applied mechanics},
     pages = {411 - 424},
     publisher = {mathdoc},
     volume = {31},
     number = {3-4},
     year = {2004},
     url = {http://geodesic.mathdoc.fr/item/TAM_2004_31_3-4_a9/}
}