@article{GerhardKuenstlerGoerneetal.2000,
  author    = {Gerhard, Reimund and K{\"u}nstler, Wolfgang and G{\"o}rne, Thomas and Pucher, Andreas and Weinhold, Till and Seiß, Martin and Xia, Zhongfu and Wedel, Armin and Danz, Rudi},
  title     = {Porous polytetrafluoroethylene space-charge electrets for piezoelectrical applications},
  year      = {2000},
  language  = {en}
}
@article{KuenstlerXiaWeinholdetal.2000,
  author    = {K{\"u}nstler, Wolfgang and Xia, Zhongfu and Weinhold, Till and Pucher, Andreas and Gerhard, Reimund},
  title     = {Piezoelectricity of porous polytetrafluoroethylene single- and multiple-film electrets containing high charge densities of both polarities},
  year      = {2000},
  language  = {en}
}