Becerra, A.; Delaye, L.; Islas, S.; Lazcano, A. 2007: The very early stages of biological evolution and the nature of the last common ancestor of the three major cell domains. Annual review of ecology, evolution, and systematics, 38: 361–379.
C. Woese, O. Kandler, M. Wheelis: Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya. Proc. Natl. Acad. Sci. U.S.A. 87(12): 4576–9 (1990). PMID 2112744
Betsey Dexter Dyer A Field Guide to Bacteria (Comstock Book) 2003: Cornell University Press. 355 pp.
Steel K.J. & S.T. Cowan 2004: Cowan and Steel's Manual for the Identification of Medical Bacteria. Cambridge University Press.