Paul Douglas Lockhart. Denmark in the Thirty Years' War, 1618-1648: King Christian IV and the Decline of the Oldenburg State. Selinsgrove, PA and Cranbury, NJ: Associated University Presses, 1996.
Paul Douglas Lockhart. Frederik II and the Protestant Cause: Denmark's Role in the Wars of Religion, 1559-1596. Leiden: Brill, 2004.
Paul Douglas Lockhart. Sweden in the Seventeenth Century. Houndmills: Palgrave Macmillan UK, 2004.
Paul Douglas Lockhart. Denmark, 1513-1660: The Rise and Decline of a Renaissance Monarchy. Oxford: Oxford University Press UK, 2007.
Paul Lockhart. The Drillmaster of Valley Forge: The Baron de Steuben and the Making of the American Army. New York: Smithsonian Books/HarperCollins, 2008.
Paul Lockhart. The Whites of Their Eyes: Bunker Hill, the First American Army, and the Emergence of George Washington. New York: HarperCollins, 2011.
Paul Lockhart. Firepower: Weapons Technology and the Art of War, 1400-1945. New York: Basic Books, 2020.