Laubichler, M. D., & Sarkar, S. (2002). Flies, genes, and brains: Oskar Vogt, Nicolai Timofeeff-Ressovsky, and the origin of the concepts of penetrance and expressivity. In L. S., Parker, & R. A., Ankeny (Eds.), Mutating concepts, evolving disciplines: genetics, medicine and society (pp. 63-85). Dordrecht: Kluwer.