Letwin, W., Child, J., & Culpeper, T. (1959). Sir Josiah Child, merchant economist, with a reprint of Brief observations concerning trade and interest of money, 1668. Baker Library, Harvard Graduate School of Business Administration.

Letwin, William, Josiah Child, and Thomas Culpeper. Sir Josiah Child, Merchant Economist, with a Reprint of Brief Observations Concerning Trade and Interest of Money, 1668. Boston: Baker Library, Harvard Graduate School of Business Administration, 1959.

Letwin, William, et al. Sir Josiah Child, Merchant Economist, with a Reprint of Brief Observations Concerning Trade and Interest of Money, 1668. Baker Library, Harvard Graduate School of Business Administration, 1959.