Gravitational lensing around Kehagias–Sfetsos compact objects surrounded by plasma Sudipta Hensh, Ahmadjon Abdujabbarov, Jan Schee and Zdeněk Stuchlík Eur. Phys. J. C, 79 6 (2019) 533 Published online: 21 June 2019 DOI: 10.1140/epjc/s10052-019-7034-7