A case study of research on general relativity that relies on comparison, from Understanding Science.
A case study of research on extinction that relies on comparison, from Understanding Science.
Stanford University - An online exhibit of historical cigarette advertising.
BibliOdyssey - A collection of images from a first edition copy of Tyson's classic work.
Richard Doll & A. Bradford Hill (1950) - Full text of the article published in the British Medical Journal.
Google - Research database allows searching of the scholarly literature.