See, among others, Klein and Goldberger (1955) and De Menil and Enzler (1972), as well as Ando and Brayton (1995). See Phelps (1967), Friedman (1968) and Lucas (1976). For a modern perspective on the Phillips curve, see Hazell et al. (2022).
But is there more to the story than appears at first glance? Evidence is emerging that the relationship between income and democracy is nonlinear. Similarly, crises and shocks appear to impact similar institutions in different countries differently. 2/3  BIS - Central bankers' speeches  Indeed, there is a powerful narrative that every crisis is an opportunity for better adjustments.