During Hayek's years at the University of Vienna, Carl Menger's work on the explanatory strategy of social science and Friedrich von Wieser's commanding presence in the classroom left a lasting influence on him. Upon the completion of his examinations, Hayek was hired by Ludwig von Mises on the recommendation of Wieser as a specialist for the Austrian government working on the legal and economic details of the Treaty of Saint Germain. Between 1923 and 1924 Hayek worked as a research assistant to Prof. Jeremiah Jenks of New York University, compiling macroeconomic data on the American economy and the operations of the US Federal Reserve.

What work did Hayek begin in 1923?