Ferrentino, R., and L. Vota. “A Mathematical Model for the Study of the Effects of the Economic Cycle on the Real GDP Growth Rate through the Expectations-Adjusted Phillips Curve”. International Journal of Economics and Financial Issues, vol. 10, no. 2, Mar. 2020, pp. 222-34, https://www.econjournals.com/index.php/ijefi/article/view/9236.