Backward propagating branch of surface waves in a semi-bounded streaming plasma system Young Kyung Lim, Myoung-Jae Lee, Ki Wan Seo and Young-Dae Jung Eur. Phys. J. D, 71 6 (2017) 151 Published online: 13 June 2017 DOI: 10.1140/epjd/e2017-70811-9