1. Kuhn T. S., The Structure of Scientific Revolutions, ed. 2 (Univ. of Chicago Press, Chicago, 1970).
2. Comets
3. See entry on W. D. Hamilton at http://en.wikipedia.org/wiki/The_Genetical_Theory_of_Natural_Selection.
4. Brock W. H., The Norton History of Chemistry (Norton, New York, 1993).
5. Meselson, Stahl, and the Replication of DNA