@article{Weigand1991,
  author    = {Weigand, Christoph},
  title     = {A Solution to the Scheduling Problem Taking into Account Quality},
  series = {Operations research '91 : extended abstracts of the 16th Symposium on Operations Research held at the University of Trier at September 9 - 11, 1991 / [GM{\"O}OR]. Peter Gritzmann ... (eds.)},
  journal   = {Operations research '91 : extended abstracts of the 16th Symposium on Operations Research held at the University of Trier at September 9 - 11, 1991 / [GM{\"O}OR]. Peter Gritzmann ... (eds.)},
  publisher = {Physica-Verl.},
  address   = {Heidelberg},
  isbn      = {3790806080},
  pages     = {373 -- 375},
  year      = {1991},
  language  = {en}
}
@article{FassbenderVogler1991,
  author    = {Faßbender, Heinz and Vogler, Heiko},
  title     = {A narrowing machine for the functional logic language BABEL, restricted to primitive recursion : abstract},
  series = {Granada Workshop on the Integration of Functional and Logic Programming / Granada Workshop on the Integration of Functional and Logic Programming <1990>. K. Indermark ... (ed.)},
  journal   = {Granada Workshop on the Integration of Functional and Logic Programming / Granada Workshop on the Integration of Functional and Logic Programming <1990>. K. Indermark ... (ed.)},
  publisher = {RWTH, Fachgruppe Informatik},
  address   = {Aachen},
  pages     = {95 -- 96},
  year      = {1991},
  language  = {en}
}
@article{Grotendorst1991,
  author    = {Grotendorst, Johannes},
  title     = {A Maple package for transforming series, sequences and functions},
  series = {Computer Physics Communications. 67 (1991), H. 2},
  journal   = {Computer Physics Communications. 67 (1991), H. 2},
  isbn      = {0010-4655},
  pages     = {325 -- 342},
  year      = {1991},
  language  = {en}
}
@article{AletseeBaumann1991,
  author    = {Aletsee, Ludwig and Baumann, Marcus},
  title     = {A laboratory incubator equipped with facilities to automatically simulate natural irradiance},
  series = {Boletim do Instituto Oceanogr{\´a}fico / Universidade de S{\~a}o Paulo},
  volume    = {Vol. 39},
  journal   = {Boletim do Instituto Oceanogr{\´a}fico / Universidade de S{\~a}o Paulo},
  number    = {No. 2},
  issn      = {1982-436X; 0080-6331},
  pages     = {155 -- 159},
  year      = {1991},
  language  = {en}
}