Martin Hellwig, "The Demand for Money and Bonds in Continuous-Time Models," Journal of Economic Theory 11, 462-464 (1975).

Martin Hellwig and Duncan Foley, "Asset Management with Trading Uncertainty," Review of Economic Studies 42, 327-346 (1975).

Martin Hellwig and Duncan Foley, "A Note on the Budget Constraint in a Model of Borrowing," Journal of Economic Theory 11, 305-314 (1975).