Nanohertz gravitational waves from supergravity inflationary model with double-inflection-point Tie-Jun Gao, Ke-Sheng Sun and Xiu-Yi Yang Eur. Phys. J. C, 84 2 (2024) 188 Published online: 26 February 2024 DOI: 10.1140/epjc/s10052-024-12560-9