@article{AIHPA_1989__50_3_369_0,
     author = {Fran\c{c}oise, J. P. and Ragnisco, O.},
     title = {Matrix second-order differential equations and hamiltonian systems of quartic type},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {369--375},
     publisher = {Gauthier-Villars},
     volume = {50},
     number = {3},
     year = {1989},
     mrnumber = {1017970},
     zbl = {0695.58012},
     language = {en},
     url = {http://www.numdam.org/item/AIHPA_1989__50_3_369_0/}
}