@inproceedings{Poisson,
  series = {Bulletin of Symbolic Logic},
  volume = {20},
  year = {2014},
  number = {2},
  author = {Akitoshi Kawamura and Florian Steinberg and Martin Ziegler},
  title = {Complexity of Laplace's and Poisson's Equation},
  pages = {231},
}