Fogel, R. W., & Engerman, S. L. (1974). Time on the cross: The economics of American Negro slavery (First edition.). Little, Brown.

Fogel, Robert William, and Stanley L. Engerman. Time on the Cross: The Economics of American Negro Slavery. First edition. Boston: Little, Brown, 1974.

Fogel, Robert William, and Stanley L. Engerman. Time on the Cross: The Economics of American Negro Slavery. First edition. Little, Brown, 1974.