@article{Baumgaertel2011,
  author    = {Hellmut Baumg{\"a}rtel},
  title     = {A Characteristic decay semigroup for the resonances of trace class perturbations with analyticity conditions of semibounded hamiltonians},
  journal   = {International journal of theoretical physic},
  volume    = {50},
  number    = {7},
  pages     = {2002 -- 2008},
  doi       = {10.1007/s10773-010-0533-9},
  year      = {2011},
}