1. Darwin Correspondence Project, Cambridge University.
2. Charles Bradlaugh; a Record of His Life and Work;Bonner,1895
3. Social moral epistemology;Buchanan;Social Philosophy and Policy,2002
4. Institutions, beliefs and ethics: eugenics as a case study;Buchanan;Journal of Political Philosophy,2007
5. “A Dirty, Filthy Book”;Chandrasekhar,1981