United States. Department of the Treasury. "Annual Report of the Director of the Bureau of Statistics," in United States. Department of the Treasury. "Report of the Secretary of the Treasury on the State of the Finances for the Year 1868," Annual Report of the Secretary of the Treasury on the State of the Finances (1868) : 467-493. https://fraser.stlouisfed.org/title/194/item/5512/toc/33037 , accessed on April 17, 2024.