Peter Senge (2012). “Schools That Learn (updated and revised second edition): A Fifth Discipline Fieldbook for Educators, Parents, and Everyone Who Cares About Education”, p.100, Nicholas Brealey Publishing
James Madison (1836). “The Debates in the Several State Conventions on the Adoption of the Federal Constitution: As Recommended by the General Convention at Philadelphia, in 1787. Together with the Journal of the Federal Convention, Luther Martin's Letter, Yate's Minutes, Congressional Opinions, Virginia and Kentucky Resolutions of '98-'99, and Other Illustrations of the Constitution”