Lyapunov exponent, ISCO and Kolmogorov–Senai entropy for Kerr–Kiselev black hole Monimala Mondal, Farook Rahaman and Ksh. Newton Singh Eur. Phys. J. C, 81 1 (2021) 84 Published online: 26 January 2021 DOI: 10.1140/epjc/s10052-021-08888-1