Dynamical theory of photon superradiative emission by nanoscale system of Bose-condensed magnons Sergey N. Andrianov and Sergey A. Moiseev Eur. Phys. J. B, 90 9 (2017) 165 Published online: 04 September 2017 DOI: 10.1140/epjb/e2017-80328-8