@phdthesis{Lueders1992,
  author    = {L{\"u}ders, Otfried},
  title     = {{\"A}quivalenzen und Dualit{\"a}ten von Variet{\"a}ten und Quasivariet{\"a}ten die von endlichen Algebren erzeugt werden},
  pages     = {111, II Bl. : Ill.},
  year      = {1992},
  language  = {de}
}
@article{DeneckeLueders1995,
  author    = {Denecke, Klaus-Dieter and L{\"u}ders, Otfried},
  title     = {Category equivalences of clones},
  year      = {1995},
  language  = {en}
}
@article{DeneckeLueders2001,
  author    = {Denecke, Klaus-Dieter and L{\"u}ders, Otfried},
  title     = {Categorical Equivalences and Invariant Relations},
  year      = {2001},
  language  = {en}
}