John Adams, Charles Francis Adams (1851). “The Works of John Adams, Second President of the United States: With a Life of the Author, Notes and Illustrations”, p.462
John Adams' letter to Benjamin Rush (December 21, 1809), as quoted in "No, Mr. Beck, John Adams Did Not Think Governments Must Be Administered by the Holy Ghost" by Chris Rodda, www.huffingtonpost.com. June 16, 2010.