* http://www.cooperativeindividualism.org/beard_constitution.html
* http://www.spartacus.schoolnet.co.uk/USAbeardC.htm - Mentions the Quaker thing.

== References ==

;Title: Charles Beard: Civilization and the Revolt Against Empiricism
;Author(s): Marcell, David W.
;Source: American Quarterly, Vol. 21, No. 1. (Spring, 1969), pp. 65-86.
;Stable URL: http://links.jstor.org/sici?sici=0003-0678%28196921%2921%3A1%3C65%3ACBCATR%3E2.0.CO%3B2-Y