8. See Philippe Artzner and Freddy Delbaen, “Default Risk Insurance and Incomplete Markets,” Mathematical Finance 5 (1995), pp. 187–195; Robert A. Jarrow and Stuart M. Turnbul, “Pricing Derivatives on Financial Securities Subject to Credit-Risk,” Journal of Finance 50 (1995), pp. 53–86; and Darrell Duffie and Kenneth J. Singleton, “Modeling Term Structures of Defaultable Bonds,” Review of Financial Studies 12 (1999), pp. 687–720.