Andrew Johnson, Benjamin Perley Poore (1868). “Trial of Andrew Johnson: President of the United States, Before the Senate of the United States, on Impeachment by the House of Representatives for High Crimes and Misdemeanors”, p.326
Andrew Johnson (1860). “The Constitutionality and Rightfulness of Secession: Speech of Hon. Andrew Johnson, of Tennessee, in the Senate of the United States ... December 18 and 19, 1860”