„Richard Popkin“: Munur á milli breytinga

*Popkin, R. ''The History of Scepticism from Savonarola to Bayle'' (Oxford: University Press, 2003). ISBN 01951076830-19-510768-3

*Popkin, R. og Stroll, Avrum. ''Philosophy Made Simple'' (Made Simple, 1993). ISBN 03854253330-385-42533-3

*Popkin, R. ''The Columbia History of Western Philosophy'' (New York: Columbia University Press, 1999). ISBN 02311012870-231-10128-7