Evolution begins with the inheritance of gene variations.
- Mangelsdorf, Paul C., 1955, George Harrison Shull: a Biography, Genetics, 40: frontpiece, Genetics Society of America.
- Moore, John, A., 1985, Science as a Way of Knowing, American Society of Zoologists.
- Rushton, Alan R., 1994, Genetics and Medicine in the United States 1800 to 1922, Johns Hopkins University Press, Baltimore.
- Stubbe, Hans, 1972 (English Translation), History of Genetics, The Massachusetts Institute of Technology, Cambridge, Massachusetts.