1. Darwin, C. On the Origin of Species by Means of Natural Selection (John Murray, London, 1859).
2. Ryan, F. Darwin's Blind Spot (Houghton Mifflin Company, Boston, 2002). This excellent, clearly written book covers all aspects of the controversy between Darwinian evolution and symbiogenesis, and explains the role of symbiogenesis in evolution.
3. deBary, H. A. Die Erscheinung der Symbiose (Strasburg, 1879).
4. Mayo, M. A., Taliansky, M. E. & Fritsch, C. in Satellites and Defective RNAs (eds Vogt, P. K. & Jackson, O.) 65–79 (Springer, 1999).
5. Sapp, J. Evolution by Association, A History of Symbiosis (Oxford University Press, New York, 1994).