@book{Liebers2002,
  author    = {Liebers, Klaus},
  title     = {Physik : Kl. 9/10, Lehrerbd., Mittelschule Sachsen},
  editor    = {Mikelskis, Helmut and Wilke, Hans-Joachim},
  publisher = {Volk und Wissen},
  address   = {Berlin},
  isbn      = {3-06-022234-7},
  pages     = {64 S.},
  year      = {2002},
  language  = {de}
}
@book{Liebers2002,
  author    = {Liebers, Klaus},
  title     = {Physik plus : Kl. 9, Arbeitsh., Gymnasium Th{\"u}ringen},
  editor    = {Mikelskis, Helmut and Wilke, Hans-Joachim},
  publisher = {Cornelsen},
  address   = {Berlin},
  isbn      = {3-06-020984-7},
  pages     = {48 S.},
  year      = {2002},
  language  = {de}
}
@book{LiebersBreuer2002,
  author    = {Liebers, Klaus and Breuer, Elmar},
  title     = {Physik plus : mit f{\"a}cher{\"u}bergreifenden Themen und Projektangeboten ; Kl. 9/10, [Hauptbd.], Gymnasium Th{\"u}ringen},
  editor    = {Mikelskis, Helmut and Wilke, Hans-Joachim},
  publisher = {Cornelsen},
  address   = {Berlin},
  isbn      = {3-06-020983-9},
  pages     = {192 S.},
  year      = {2002},
  language  = {de}
}