1. Andrea L. Volpe, “The Cartes De Visite Craze,” The New York Times, August 6, 2013.
  2. Oliver Wendell Holmes, Sr., “Doings of the Sunbeam,” The Atlantic Monthly, July 1863, 8, as quoted in Volpe.
  3. “Picture This: Frederick Douglass Was The Most Photographed Man Of His Time,” National Public Radio, December 13, 2015.