Fleeming Jenkin, 1870. "The Graphical Representation of the Laws of Supply and Demand, and their Application to Labour," in Alexander Grant, ed., Recess Studies, Edinburgh. ch. VI, pp. 151–85. Edinburgh. Scroll to chapter link.
Thomas M. Humphrey, 1992. "Marshallian Cross Diagrams and Their Uses before Alfred Marshall," Economic Review, Mar/Apr, Federal Reserve Bank of Richmond, pp. 16–21.