New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms.

@article{Whittaker1969NewCO,
  title={New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms.},
  author={Robert H. Whittaker},
  journal={Science},
  year={1969},
  volume={163 3863},
  pages={150-60}
}