The general operator form for the total-momentum-dependent nucleon-nucleon potential Kacper Topolnicki, Jacek Golak, Roman Skibiński and Henryk Witała Eur. Phys. J. A, 52 7 (2016) 188 Published online: 19 July 2016 DOI: 10.1140/epja/i2016-16188-8