@book{Grueters1987,
  author    = {Gr{\"u}ters, Hugo},
  title     = {Mechanik: Vorlesung},
  publisher = {Becker-Kuns},
  address   = {Aachen},
  pages     = {253 S.: zahlr. graph. Darst.},
  year      = {1987},
  language  = {de}
}
@book{Grueters1987,
  author    = {Gr{\"u}ters, Hugo},
  title     = {Aufgabensammlung Mechanik / von Hugo Gr{\"u}ters},
  publisher = {Becker-Kuns},
  address   = {Aachen},
  pages     = {Getr. Z{\"a}hlung : graph. Darst.},
  year      = {1987},
  language  = {de}
}