Semileptonic $$B_c$$ meson decays to S-wave charmonium statesSonali Patnaik, Lopamudra Nayak, P. C. Dash, Susmita Kar and N. BarikEur. Phys. J. Plus, 135 11 (2020) 936DOI: https://doi.org/10.1140/epjp/s13360-020-00898-4