National Bureau of Economic Research. (1960). Trends in the American Economy in the 19th century Vol.24: Studies in income and wealth (24.).

National Bureau of Economic Research. Trends in the American Economy in the 19th Century Vol.24: Studies in Income and Wealth. 24. Princeton University Press, Princeton, 1960.

National Bureau of Economic Research. Trends in the American Economy in the 19th Century Vol.24: Studies in Income and Wealth. 24. 1960.