@article{DeneckePabhapote2001,
  author    = {Denecke, Klaus-Dieter and Pabhapote, Nittiya},
  title     = {Tree-recognizers and tree-hyperrecognizers},
  year      = {2001},
  language  = {en}
}
@article{Denecke2001,
  author    = {Denecke, Klaus-Dieter},
  title     = {Hyperidentities in semigroups},
  isbn      = {90-5199-490-7},
  year      = {2001},
  language  = {en}
}
@article{ArwornDeneckeKoppitz2001,
  author    = {Arworn, Srichan and Denecke, Klaus-Dieter and Koppitz, J{\"o}rg},
  title     = {Strongly luid and weakly unsolid varieties},
  issn      = {1346-0862},
  year      = {2001},
  language  = {en}
}
@article{ArwornDenecke2001,
  author    = {Arworn, Srichan and Denecke, Klaus-Dieter},
  title     = {Tree Transformations defined by Hypersubstitutions},
  issn      = {1509 - 9415},
  year      = {2001},
  language  = {en}
}
@article{DeneckeKoppitzWismath2001,
  author    = {Denecke, Klaus-Dieter and Koppitz, J{\"o}rg and Wismath, Shelly},
  title     = {The semantical hyperunification problem},
  year      = {2001},
  language  = {en}
}
@article{DeneckeLeeratanavalee2001,
  author    = {Denecke, Klaus-Dieter and Leeratanavalee, Sorasak},
  title     = {M-solid polynomial varieties of semigroups},
  year      = {2001},
  language  = {en}
}
@article{DeneckeLueders2001,
  author    = {Denecke, Klaus-Dieter and L{\"u}ders, Otfried},
  title     = {Categorical Equivalences and Invariant Relations},
  year      = {2001},
  language  = {en}
}
@book{DeneckeKoppitzShtraklov2001,
  author    = {Denecke, Klaus-Dieter and Koppitz, J{\"o}rg and Shtraklov, Slavcho},
  title     = {The Depth of a Hypersubstitution},
  year      = {2001},
  language  = {en}
}
@article{DeneckeKoppitz2001,
  author    = {Denecke, Klaus-Dieter and Koppitz, J{\"o}rg},
  title     = {Fluid, unsolid and completely unsolid varieties},
  year      = {2001},
  language  = {en}
}
@article{DeneckeKoppitz2001,
  author    = {Denecke, Klaus-Dieter and Koppitz, J{\"o}rg},
  title     = {Essential variables in hypersubstitution},
  year      = {2001},
  language  = {en}
}