@article{AIHPA_1993__59_4_399_0,
     author = {Hayward, Sean A.},
     title = {Dual-null dynamics},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {399--419},
     publisher = {Gauthier-Villars},
     volume = {59},
     number = {4},
     year = {1993},
     mrnumber = {1254979},
     zbl = {0794.70009},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1993__59_4_399_0/}
}