@article{AIHPA_1991__55_2_707_0,
     author = {Oliva, W. M.},
     title = {On the chaotic behavior and the non-integrability of the four vortices problem},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {707--718},
     publisher = {Gauthier-Villars},
     volume = {55},
     number = {2},
     year = {1991},
     mrnumber = {1139542},
     zbl = {0738.76008},
     language = {en},
     url = {http://www.numdam.org/item/AIHPA_1991__55_2_707_0/}
}