Distinguishing black holes with and without spontaneous scalarization in Einstein-scalar-Gauss–Bonnet theories via optical featuresXi-Jing Wang, Yuan Meng, Xiao-Mei Kuang and Kai LiaoEur. Phys. J. C, 84 12 (2024) 1243DOI: https://doi.org/10.1140/epjc/s10052-024-13612-w