1. Borio, Claudio, Piti Disyatat, Mikael Juselius, and Phurichai Rungcharoenkitkul. 2017. Why so low for so long? A long-term view of real interest rates. Bank for International Settlements Working Papers No. 685.
2. Bullard, James. 2016. The St. Louis Fed’s new characterization of the outlook for the U.S. economy. Federal Reserve Bank of St. Louis. Announcement. https://www.stlouisfed.org/~/media/Files/PDFs/Bullard/papers/Regime-Switching-Forecasts-17June2016.pdf?la=en .
3. Cúrdia, Vasco. 2015. Why so slow? A gradual return for interest rates. Federal Reserve Bank of San Francisco. Economic Letter No. 2015–32.
4. Del Negro, Marco, Domenico Giannone, Marc Giannoni, and Andrea Tambalotti, 2017. Safety, liquidity and the natural rate of interest. Brookings Papers on Economic Activity. Spring: 235–294.
5. Dupor, William. 2015. Liftoff and the natural rate of interest. Federal Reserve Bank of St. Louis. On the Economy. https://www.stlouisfed.org/on-the-economy/2015/june/liftoff-and-the-natural-rate-of-interest .