Solving procedure for the motion of infinitesimal mass in BiER4BP Sergey Ershkov, Dmytro Leshchenko and Alla Rachinskaya Eur. Phys. J. Plus, 135 7 (2020) 603 Published online: 27 July 2020 DOI: 10.1140/epjp/s13360-020-00579-2