@phdthesis{Changphas2004,
  author    = {Changphas, Thawhat},
  title     = {Monoids of Hypersubstitutions},
  address   = {Potsdam},
  pages     = {vii, 88 S.},
  year      = {2004},
  language  = {en}
}
@phdthesis{Romanovskiy2004,
  author    = {Romanovskiy, Nikolai},
  title     = {Systems of elasticity theory},
  pages     = {59 S.},
  year      = {2004},
  language  = {en}
}