@article{Alt1978,
  author    = {Alt, Helmut},
  title     = {Wirtschaftlichkeit von Investitionen},
  series = {Elektrizit{\"a}tswirtschaft},
  volume    = {77},
  journal   = {Elektrizit{\"a}tswirtschaft},
  number    = {3},
  publisher = {VWEW-Energieverlag},
  address   = {Frankfurt/Main},
  issn      = {0013-5496},
  pages     = {73 -- 76},
  year      = {1978},
  language  = {de}
}
@article{Alt1978,
  author    = {Alt, Helmut},
  title     = {Tabellenfreie Berechnung der Einkommensteuer mit Hilfe des programmierbaren Taschenrechners},
  series = {Elektrizit{\"a}tswirtschaft},
  volume    = {77},
  journal   = {Elektrizit{\"a}tswirtschaft},
  publisher = {VWEW-Energieverlag},
  address   = {Frankfurt/Main},
  issn      = {0013-5496},
  pages     = {486 -- 489},
  year      = {1978},
  language  = {de}
}
@article{Alt1978,
  author    = {Alt, Helmut},
  title     = {Intervallschalter mit getrennt einstellbarer Pulszeit und Pulszahl},
  series = {Elektronik : Fachmedium f{\"u}r industrielle Anwender und Entwickler},
  volume    = {27},
  journal   = {Elektronik : Fachmedium f{\"u}r industrielle Anwender und Entwickler},
  number    = {H. 14},
  publisher = {WEKA Fachmedien},
  address   = {Haar},
  issn      = {0013-5658},
  pages     = {76},
  year      = {1978},
  language  = {de}
}