@unpublished{KytmanovMyslivetsTarkhanov2008,
  author  = {Aleksandr Kytmanov and Simona Myslivets and Nikolai Nikolaevich Tarkhanov},
  title   = {Zeta-function of a nonlinear system},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprint},
  number    = {(2004) 19},
  year    = {2008},
}