@article{AIHPA_1978__28_2_197_0,
     author = {Davis, W. R. and Oliver, D. R.},
     title = {Matter field space times admitting symmetry mappings satisfying vanishing contraction of the {Lie} deformation of the {Ricci} tensor},
     journal = {Annales de l'institut Henri Poincar\'e. Section A, Physique Th\'eorique},
     pages = {197--206},
     publisher = {Gauthier-Villars},
     volume = {28},
     number = {2},
     year = {1978},
     zbl = {0375.53010},
     mrnumber = {489668},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1978__28_2_197_0/}
}