J. Burdon Sanderson: On the Origin of Biology and its Relation to Other Branches of Natural Science (html/gif) (Volume 2(1707): sivut 613–617. Being a part of the Presidential Address delivered before the British Association for the Advancement of Science at Nottingham on September 13th, 1893) British Medical Journal. 1893 September 16;. Viitattu 24.11.2010. (englanniksi)
