Henry George (1912). “Progress and Poverty: An Inquiry Into the Cause of Industrial Depressions and of Increase of Want with Increase of Wealth; the Remedy”
Frederick Douglass, George L. Ruffin (2001). “Life and Times of Frederick Douglass: His Early Life as a Slave, His Escape from Bondage, and His Complete History to the Present Time”, p.61, Digital Scanning Inc