W. E. Castle, The Laws of Heredity of Galton and Mendel, and Some Laws Governing Race Improvement by Selection, Proceedings of the American Academy of Arts and Sciences Vol. 39, No. 8 (Nov., 1903), pp. 223–242, at p. 237. Published by: American Academy of Arts & Sciences JSTOR20021870
"Thomas H. Morgan – Biographical". nobelprize.org. Les Prix Nobel. T.H. Morgan's Nobel Prize biography mentioning C. W. Woodworth's suggestion and W. E. Castle's use of Drosophila. (From Nobel Lectures, Physiology or Medicine 1922–1941, Elsevier Publishing Company, Amsterdam, 1965.) Retrieved May 14, 2018.