@article{AIHPA_1994__61_1_87_0,
     author = {W\"unsch, V.},
     title = {Huygens' principle on {Petrov} type {N} space-times},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {87--102},
     publisher = {Gauthier-Villars},
     volume = {61},
     number = {1},
     year = {1994},
     mrnumber = {1303187},
     zbl = {0814.53060},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1994__61_1_87_0/}
}