Ground-based gamma-ray astronomy: history and development of techniques D. Bose, V. R. Chitnis, P. Majumdar and B. S. Acharya Eur. Phys. J. Spec. Top., 231 1 (2022) 3-26 Published online: 30 December 2021 DOI: 10.1140/epjs/s11734-021-00396-3