@article{AIHPA_1968__9_3_273_0,
     author = {Kichenassamy, S.},
     title = {Null electromagnetic fields in algebraically special {Petrov} type spaces},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {273--281},
     publisher = {Gauthier-Villars},
     volume = {9},
     number = {3},
     year = {1968},
     mrnumber = {245292},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AIHPA_1968__9_3_273_0/}
}