@article{ShlapunovTarkhanov2007,
  author    = {Alexander Shlapunov and Nikolai Nikolaevich Tarkhanov},
  title     = {Formal poincare lemma},
  journal   = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell},
  year      = {2007},
}