Solutions of the Klein-Gordon equation with the improved Rosen-Morse potential energy model Tao Chen, Shu-Rong Lin and Chun-Sheng Jia Eur. Phys. J. Plus, 128 7 (2013) 69 Published online: 01 July 2013 DOI: 10.1140/epjp/i2013-13069-1