(en) Ulysses S. Grant, Grant: Memoirs and Selected Letters: Personal Memoirs of U.S. Grant and Selected Letters, 1839-1865, The Library of America (lire en ligne), p. 41.
(en) Fred I. Greenstein, « The Policy-Driven Leadership of James K. Polk: Making the Most of a Weak Presidency », Presidential Studies Quarterly, vol. 40, no 4, , p. 732 (DOI10.1111/j.1741-5705.2010.03808.x, JSTOR23044848).
(en) Fred I. Greenstein, « The Policy-Driven Leadership of James K. Polk: Making the Most of a Weak Presidency », Presidential Studies Quarterly, vol. 40, no 4, , p. 732 (DOI10.1111/j.1741-5705.2010.03808.x, JSTOR23044848).