Gentile, R., F. Porco, D. Raffaele, and G. Uva. “Simplified Moment-Curvature Relationship in Analytical Form for Circular RC Sections”. Bulletin of the New Zealand Society for Earthquake Engineering, vol. 51, no. 3, Sept. 2018, pp. 145-58, doi:10.5459/bnzsee.51.3.145-158.