L. Randall Wray gives a quick description of Hyman Minsky’s financial instability hypothesis (FIH) (Minsky 1982; 1986; 1992; 2008 ), which took up ideas from Irving Fisher (Fisher 1933). This has been further developed in Post Keynesian economics, most notably by Steve Keen.
The good news is that the Fisher–Minsky approach has filtered through to New Keynesians like Krugman, even if Krugman does not understand it properly, by failing to see the role debt plays in aggregate demand and the endogeneity of credit money, as shown by Steve Keen (see “‘Like a Dog Walking on its Hind Legs’: Krugman’s Minsky Model,” Debtdeflation.com, March 4th, 2011).
Fisher, I. 1933. “The Debt-Deflation Theory of Great Depressions,” Econometrica 1.4: 337–357.
Minsky, H. P. 1982. Can “It” Happen Again?: Essays on Instability and Finance, M.E. Sharpe, Armonk, N.Y.
Minsky, H. P. 1986. Stabilizing an Unstable Economy, Yale University Press, New Haven and London.
N.B. Steve Keen thinks this is Minsky’s worst book. Consult Minsky (1982) and (2008)  instead for the best statements of the FIH.
Minsky, H. P. 1992. The Financial Instability Hypothesis, Working papers (Jerome Levy Economics Institute) ; no. 74.
Minsky, H. P. 2008 . John Maynard Keynes, McGraw-Hill, New York and London.