Chapter 27. Jack R. Harlan. 1977. Sources of genetic defense. Pages 345-356. In: Peter R. Day (editor). The Genetic Basis of Epidemics in Agriculture. Annals of the New York Academy of Sciences No. 287. The New York Academy of Sciences, New York, New York, 400 pages.

Keywords: the most common host-pathogen relationship is immunity of the host and avirulence of the pathogen, a corollary is that completely disease-free individual is almost unknown, geographic sources, resistances to nine diseases in Ethiopian barley, sources of resistance in rice, taxonomic sources,