Wheeler, Quentin D. (2004). "Taxonomic triage and the poverty of phylogeny". in H. C. J. Godfray & S. Knapp. Taxonomy for the twenty–first century. 359. 571–583. doi:10.1098/rstb.2003.1452.
Small, Ernest (1989). "Systematics of Biological Systematics (Or, Taxonomy of Taxonomy)". Taxon38 (3): 335–356. doi:10.2307/1222265.
Copeland, H. (1938). "The kingdoms of organisms". Quarterly Review of Biology13: 383–420. doi:10.1086/394568.
Copeland, H. F. (1956). The Classification of Lower Organisms. Palo Alto: Pacific Books. doi:10.5962/bhl.title.4474.
Woese, C. R.; Balch, W. E.; Magrum, L. J.; Fox, G. E.; Wolfe, R. S. (August 1977). "An ancient divergence among the bacteria". Journal of Molecular Evolution9 (4): 305–311. doi:10.1007/BF01796092. பப்மெட்:408502.
Woese, C. R.; Balch, W. E.; Magrum, L. J.; Fox, G. E.; Wolfe, R. S. (August 1977). "An ancient divergence among the bacteria". Journal of Molecular Evolution9 (4): 305–311. doi:10.1007/BF01796092. பப்மெட்:408502.